 their radiological features suggest malignant neoplasms , whereas they are not  ct and mr imaging are the most used tools in their evaluation 
inflammatory myofibroblastic tumours ( imts ) constitute a rare group of neoplasms composed of a mixture of spindle - shaped myofibroblasts or fibroblasts and a variable amount of inflammatory cells ( eosinophils , plasma cells and lymphocytes ) .
many different terms have been used to refer to these tumours : plasma cell granuloma , inflammatory myofibrohistiocytic proliferation , fibroxanthoma , xanthogranuloma .
the most frequently affected organs are lung and orbit , but they have been described in nearly every organ .
different aetiologies have been proposed for imt , being different chronic infections , autoimmune diseases and trauma the most accepted .
specific inflammatory diseases , such as igg4 disease , have also been recently associated [ 4 , 5 ] .
an aggressive behaviour with metastases has been described [ 3 , 6 , 7 ] .
clinical presentation of imts depends on the organ in which they arise , but they frequently associate general inflammatory symptoms as fever or malaise . radiological appearance of imts is unspecific and they are often misdiagnosed as malignant neoplasms .
many of them are incidentally discovered when an imaging technique ( computed tomography [ ct ] , ultrasonography [ us ] or magnetic resonance imaging [ mri ] ) is performed for any other reason .
their most common radiological presentation is as solid , irregular , well - defined masses .
immunohistochemical studies of t- and b - cell subpopulations , cd34 , cd117 , s-100 and c - kit may be helpful in distinguishing imts from other soft - tissue neoplasms [ 8 , 9 ] . at the molecular level ,
approximately half of imts contain a clonal cytogenetic aberration that activates the anaplastic lymphoma kinase ( alk- ) .
positive immunohistochemical staining of alk is in approximately 40100  % of imts , depending on the anatomical sites where they arise [ 810 ] .
furthermore , alk expression could be a prognostic factor of aggressiveness for imt . according to an update based on the new world health organisation ( who ) classification , imts
are considered as neoplasms which may recur or metastasise in as many as 5  % of cases .
the objective of this pictorial review is to present the most important characteristics of imts arising in different locations of the body with their histological correlation .
, these tumours can appear as hypoechoic or hyperechoic masses with ill - defined or well - circumscribed edges and a variable doppler appearance with increased vascularity .
us is usually the first imaging technique when imts appear in specific locations , such as testicles or neck . in other locations
on contrast - enhanced ct , imts can appear as homogeneous or heterogeneous lesions , with variable enhancement on delayed acquisitions due to the presence of fibrosis .
these findings are also present on gadolinium contrast - enhanced mri . on t1-weighted and t2-weighted sequences ,
imts usually show low signal intensity reflecting also the presence of fibrotic tissue ( table  1).table 1symptoms , radiological findings and differential diagnosis of the main imts of the bodysymptomsimaging findingsdifferential diagnosisorbitpain , redness , oedema , proptosis , ptosis , oculomotor deficits , diplopia , swelling , mass - effectsolid and heterogeneous enhancing .
associated retrobulbar fat or oedemagranulomatous diseases , primary infection , sarcoid , sjgren disease , primary and secondary tumours of the orbit , lymphoma and connective tissue diseaseslungcough , chest pain , dyspnea , haemoptysis , fever , malaise and weight loss.solitary , well - circumscribed , peripheral , predominance for the lower lobes , unusual calcifications .
low intensity on t2-weighted imagesmalignant lung masses : primary bronchogenic carcinomascrotumlump in the scrotumsolid and heterogeneous masses with internal vascularity on us .
small calcifications can be associatedscrotum primary neoplasmhepaticunspecific , depending on the sizeheterogeneous or peripheral enhancement during the arterial phase . or homogeneous enhancement during the arterial phase and washout during the delayed phase on ct .
t1 hypointense and t2 hyperintense with heterogeneous enhancementhccsplenicleft upper quadrant or epigastric painlow - density pattern .
low - intensity lesion in the early phase after gadolinium injection and high - intensity in the delayed phasesplenic haemangioma and other primary splenic neoplasms as lymphoma or splenic angiosarcomagrastrointestinal tract and mesenteryabdominal pain , intestinal obstruction , dysphagia , anaemiahypodense , heterogeneous , well - delimitedgist , inflammatory fibroid polyp , smooth muscle neoplasm , peripheral nerve sheath tumour , solitary fibrous tumour , fibromatosis , the follicular dendritic cell sarcoma , lymphoma and adenocarcinomamusculoskeletalpain , oedemanon - homogeneous , solidmalignant lesions : rabdomyosarcoma symptoms , radiological findings and differential diagnosis of the main imts of the body
imts have been reported in various sites in the head and neck such as bucal space , maxillary sinus , nasal cavity , parotid gland , nasopharynx and larynx ( fig . 
1pathology : imt in the left supraglottic space ( arrow ) with paraglottic space involvement indicated by replacement of the paraglottic fat with soft tissue . a axial reformation of contrast - enhanced neck ct . a solid , well - defined ,
normal tissue was present in the peripheral zone ( * ) pathology : imt in the left supraglottic space ( arrow ) with paraglottic space involvement indicated by replacement of the paraglottic fat with soft tissue . a axial reformation of contrast - enhanced neck ct .
a solid , well - defined , little - enhancing nodule in the supraglottic larynx was observed ( yellow arrow ) .
b microscopic study obtained after surgical removal of the lesion . the sample showed proliferation of fusiform cells mixed with macrophages and giant multinucleated cells .
normal tissue was present in the peripheral zone ( * ) however , the orbit is the most common location of imts .
they account for approximately 10  % of orbital masses , being the third most common cause of orbital masses .
their aetiology is unknown , but they have been associated with inmunological disorders , different infections and history of trauma .
recently , they have been strongly associated with the igg4-related sclerosing systemic inflammatory disease   and with chronic infection by epstein - barr virus .
the clinical presentation and symptoms may vary with the location , extension and aggressiveness of the tumour .
patients with imts of the orbit can present local symptoms as pain , redness , oedema , proptosis , ptosis , oculomotor deficits , diplopia , lid swelling or mass - effect and systemic symptoms due to the general inflammatory disorders they are frequently associated with .
mri is superior to ct in the evaluation of inflammation of the nerves and muscles .
they usually appear as solid and heterogeneous enhancing masses , which can affect retro bulbar fat , cause bone destruction , and present intracranial extension . when they show low intensity on t2-weighted images prominent , fibrotic composition is present ( fig . 
a , b axial and coronal mr reformations of the same patient on t2-weighted sequences showed a well - delimited , hyperintense intraorbital mass , in the intraconal compartment , in the medial aspect .
c , d t1-weighted images demonstrated a hypointense , homogeneous , well - delimited mass with peripheral enhancement after gadolinium injection .
f microscopic sample obtained after surgery demonstrated an epithelial tumour composed of fusiform cells mixed with an extensive chronic inflammatory infiltrate of plasmatic cells , lymphocytes and macrophages . in the peripheral of the sample
a , b axial and coronal mr reformations of the same patient on t2-weighted sequences showed a well - delimited , hyperintense intraorbital mass , in the intraconal compartment , in the medial aspect .
c , d t1-weighted images demonstrated a hypointense , homogeneous , well - delimited mass with peripheral enhancement after gadolinium injection .
f microscopic sample obtained after surgery demonstrated an epithelial tumour composed of fusiform cells mixed with an extensive chronic inflammatory infiltrate of plasmatic cells , lymphocytes and macrophages . in the peripheral of the sample striated muscle cells
were also observed pathologically , imts of the head and neck consist of many fibroblastic cells , fibroblastic cells and inflammatory cells , which include plasma cells and eosinophils .
the differential diagnosis includes granulomatous diseases , primary infection , sarcoid , sjgren disease , primary and secondary tumours of the orbit , lymphoma and connective tissue diseases .
the administration of corticosteroids an inmunosupresors usually leads to a decrease of size of the mass but also radiotherapy or surgery may be indicated .
they account for around the 50  % of benign pulmonary masses in children , representing only about 0.7  % of all tumours of the lung in general population . as in other organs
sometimes , imts are also related with antecedents of lung surgery and they can arise in surgical lung scars .
common clinical characteristics include unspecific respiratory symptoms , such as cough , chest pain , dyspnea , haemoptysis and unspecific inflammatory symptoms as fever , malaise and weight loss .
they usually appear as solitary , well - circumscribed peripheral lung masses , with predominance for the lower lobes   ( fig . 
on ct with intravenous contrast , they present a variable heterogeneous or homogeneous degree of enhancement pattern [ 3 , 21 ] . it has been described an aggressive behaviour with invasion of the adjacent structures . on mri
because of their similar radiological appearance to malignant lung masses , biopsy is necessary to obtain the diagnosis.fig .
a 55-year - old man with a cough and haemoptysis.a axial reformation of non - contrast ct with mediastinum window .
two solid , ill - defined nodules in right lower lobe are observed ( yellow arrows ) .
b axial reformations with lung window of the same patient where the lung nodules are shown ( white arrows ) .
c partial lobectomy of the right lower lobe specimen . note the presence of the nodules ( * ) .
d microscopic study of the resected lung sample where fusiform cells with an associated inflammatory infiltrate of lymphocytes , plasmatic cells and histiocytes was found pathology : imt of the lung . a 55-year - old man with a cough and haemoptysis.a axial reformation of non - contrast ct with mediastinum window .
two solid , ill - defined nodules in right lower lobe are observed ( yellow arrows ) .
b axial reformations with lung window of the same patient where the lung nodules are shown ( white arrows ) .
c partial lobectomy of the right lower lobe specimen . note the presence of the nodules ( * ) .
d microscopic study of the resected lung sample where fusiform cells with an associated inflammatory infiltrate of lymphocytes , plasmatic cells and histiocytes was found the treatment of choice of lung imts is surgery to exclude malignancy and to achieve the cure .
although spontaneous regression may occur , local expansion may cause significant morbidity and occasional death .
the prognosis after complete surgical resection is excellent , with a low rate of recurrence . in these cases ,
alternative treatments ( radiotherapy , corticoids or chemotherapy ) to surgery could be also used . only a few cases of imts in the spermatic cord have been reported .
the most common presentation of epididymal ( fig .  4 ) and paratesticular imts is a lump in the scrotum.fig .
4pathology : imt of the epididymus . a 40-year - old man with a lump in the scrotum . a a hypoechoic
a diffuse infiltrate composed of fibroblastic and fusiform cells mixed with inflammatory cells ( mainly lymphocytes and macrophages ) was observed pathology : imt of the epididymus . a 40-year - old man with a lump in the scrotum . a a hypoechoic , well - delimited epididymal lesion in the right scrotum was detected .
a diffuse infiltrate composed of fibroblastic and fusiform cells mixed with inflammatory cells ( mainly lymphocytes and macrophages ) was observed in the evaluation of scrotal masses , us is the most accurate imaging technique , helping to distinguish intratesticular from extratesticular lesions and solid from cystic lesions .
on ct , they appear as well - defined , hypodense masses with little enhancement after intravenous contrast injection . in some cases ,
a 34-year - old man with no relevant medical history came to our hospital with a lump in the scrotum .
a us showed an isoechoic , solid , paratesticular nodule with fine calcifications ( yellow arrow ) .
b axial reformation of contrast - enhanced ct on portal phase demonstrated a well - delimited , heterogeneous , little - enhancing mass in the right scrotum .
d microscopic study of the lesion demonstrated a well - delimited lesion constituted of fibroblasts , lymphocytes and plasmatic cells with associated lymphoid follicle .
a 34-year - old man with no relevant medical history came to our hospital with a lump in the scrotum .
a us showed an isoechoic , solid , paratesticular nodule with fine calcifications ( yellow arrow ) .
b axial reformation of contrast - enhanced ct on portal phase demonstrated a well - delimited , heterogeneous , little - enhancing mass in the right scrotum .
d microscopic study of the lesion demonstrated a well - delimited lesion constituted of fibroblasts , lymphocytes and plasmatic cells with associated lymphoid follicle .
there was no evidence of adjacent testicle invasion surgical resection without orchiectomy is the ideal treatment , but in some cases the testicle must be removed due to the size of the mass or when the mass is attached to the testis .
imts of the penis are extremely rare . to our knowledge , no imts at this location have been reported .
on ct , this tumour appeared as a well - defined , little - enhancing and non - aggressive mass surrounding the penile urethra and the corpora cavernosa with no evidence of invasion of them.fig .
a 46-year - old man with a mass in the penis came to our hospital .
he related more than 6 years of slow growth of the mass with no suspicious associated symptoms .
c , d axial and coronal reformations of enhanced - ct after the injection of intravenous contrast on portal phase .
macroscopic view showed an heterogeneous aspect due to the mixture of tissues ( solid tumour , lipoid component and areas of haemorrhage ) .
f microscopic study confirmed a mesenchymal tumour composed of fusiform cells , some of them multinucleated , with round or elongate nucleus .
a 46-year - old man with a mass in the penis came to our hospital .
he related more than 6 years of slow growth of the mass with no suspicious associated symptoms .
c , d axial and coronal reformations of enhanced - ct after the injection of intravenous contrast on portal phase .
macroscopic view showed an heterogeneous aspect due to the mixture of tissues ( solid tumour , lipoid component and areas of haemorrhage ) .
f microscopic study confirmed a mesenchymal tumour composed of fusiform cells , some of them multinucleated , with round or elongate nucleus .
no mitotic figures were observed surgical treatment was performed due to the size and non - conclusive radiological features of the tumour .
hepatic imts constitute an extremely rare group of hepatic tumours , accounting only for the 0.7  % of all the hepatic lesions .
they have been associated with autoimmune diseases , immunological disorders and viral infections , such as igg4 disease , sclerosing cholangitis , crohns disease , hepatic viral infections   and epstein - barr virus . symptoms of hepatic imts depend on their size .
on contrast - enhanced ct , they usually show heterogeneous or peripheral enhancement during the arterial phase . despite this ,
some of them present homogeneous enhancement during the arterial phase and washout during the delayed phase , which can lead to misdiagnosing them as hepatocarcinomas ( hccs )   ( fig . 
7 ) . on mri , these lesions usually are t1 hypointense and t2 hyperintense with heterogeneous enhancement ( fig .  8) .
hepatobiliary contrast ( gadoxetate disodium , primovist ; bayer healthcare , leverkusen , germany ) could be of help to differentiate hcc from imts of the liver .
on the hepatobiliary phase , high signal intensity in the centre of the lesion has been described , suggesting a benign lesion.fig .
well - defined , hypointense lesion on t1-weighted images ( a ) which presented weak enhancement in the arterial phase ( b ) and wash - out on portal and equilibrium phases ( c- , d ) located in hepatic left lobe .
f the lesion demostrated an expansive chronic inflammatory infiltrate of plasmatic cells , lymphocytes and macrophages .
a abdominal ultrasound where a slightly hypoechoic , solid , heterogeneous mass arising in the left hepatic lobe was observed .
axial t1-weighted unenhanced ( b ) and contrast - enhanced mr images ( c , d ) showed an ill - defined with heterogeneous enhancement mass located in lateral hepatic segments .
mesenchymal tumour composed of fusiform cells , lymphocytes and lipid - filled macrophages can be observed .
normal hepatocytes with large and small fatty droplet change are also present pathology : imt of the liver .
well - defined , hypointense lesion on t1-weighted images ( a ) which presented weak enhancement in the arterial phase ( b ) and wash - out on portal and equilibrium phases ( c- , d ) located in hepatic left lobe .
e macroscopic view of partial hepatectomy obtained after surgical excision of the lesion . a solid , well - defined and yellowing appearance mass is showed .
f the lesion demostrated an expansive chronic inflammatory infiltrate of plasmatic cells , lymphocytes and macrophages .
a abdominal ultrasound where a slightly hypoechoic , solid , heterogeneous mass arising in the left hepatic lobe was observed .
axial t1-weighted unenhanced ( b ) and contrast - enhanced mr images ( c , d ) showed an ill - defined with heterogeneous enhancement mass located in lateral hepatic segments .
mesenchymal tumour composed of fusiform cells , lymphocytes and lipid - filled macrophages can be observed .
normal hepatocytes with large and small fatty droplet change are also present surgery is the most accepted treatment . if there is a biopsy - proven diagnosis of imts that excludes malignancy , medical treatment with no steroidal anti - inflammatory drugs in patients with peripheral hepatic imts could be prescribed .
patients with spleen imts frequently associate unspecific symptoms as left upper quadrant or epigastric pain .
splenomegaly is common and some patients can present fever , anaemia and signs of hypersplenism .
different radiological imaging modalities have been proposed for their evaluation . on all of them ,
they are depicted as low - density masses in both non - enhanced and enhanced acquisitions ( fig . 
9 ) . on mri studies , they present low - intensity mass on both the t1- and t2-weighted images .
their typical enhancement pattern after gadolinium injection is as a low - intensity lesion in the early phase , which changes into a high - intensity one in the delayed phase .fig .
9pathology : imt of the spleen . a axial reformation of contrast - enhanced ct on portal phase .
prominent cellularity composed of an irregular , weakly basophil set of mioepithelial - fusiform cells .
numerous inflammatory cells ( plasmatic , lymphocytes and few neutrophils and eosinophils ) with isolated macrophages were also found .
no atypia or mitotic figures were present pathology : imt of the spleen . a axial reformation of contrast - enhanced ct on portal phase .
prominent cellularity composed of an irregular , weakly basophil set of mioepithelial - fusiform cells .
numerous inflammatory cells ( plasmatic , lymphocytes and few neutrophils and eosinophils ) with isolated macrophages were also found .
no atypia or mitotic figures were present the differential diagnosis includes splenic haemangioma and other primary splenic neoplasms such as lymphoma or splenic angiosarcoma . when a suspicious spleen mass is found , the treatment of choice is splenectomy due to the high risk of bleeding associated to splenic biopsy [ 8 , 31 ] .
they can arise anywhere , the stomach and small intestine being the most common locations [ 3 , 9 ] .
clinical symptoms may vary from none to abdominal pain , intestinal obstruction , dysphagia or anaemia , depending on the location and size of the mass .
contrast - enhanced ct is the imaging technique , which give us more information about of imts of the gastrointestinal tract .
they are usually found as hypodense , heterogeneous and well - delimited masses ( figs . 
axial reformation of contrast - enhanced ct on arterial ( a ) , portal ( b ) and 3 min after injection delayed ( c ) acquisitions .
a well - defined , heterogeneous nodule with moderate enhancement on portal phase arising from the gastric fundus was found ( yellow arrows ) .
d microscopic studies performed after surgical removal of the lesion demonstrated high amount of mesenchymal fusiform cells combined with vascular structures .
axial and coronal reformations of contrast - enhanced ct on portal ( a , b ) and 8 min after injection delayed acquisitions ( c , d ) .
pararectal solid and well - defined mass with moderated peripheral enhancement adjacent to the rectum and left seminal vesicle was detected .
mesenchymal neoplasm composed of polygonal cells with clear cytoplasm and round normochromatic nuclei with abundant vessels and occasional scattered inflammatory cells was observed .
mixed within the neoplasm cells , there was a chronic inflammatory infiltrate of lymphoid cells .
12pathology : metastatic imt of the appendix . a 63-year - old man with antecedents of left hemicolectomy due to colon cancer .
a axial reformation of contrast - enhanced ct on portal phase acquired seven years after partial colectomy .
an appendicular , irregular , solid mass with slight enhancement was identified ( yellow arrow ) . due to its radiological features ,
b axial reformation of contrast - enhanced ct on portal phase performed 8 months later showed a significant growth of the appendicular mass with extension and infiltration of the adjacent small bowel loops .
axial reformation of contrast - enhanced ct on arterial ( a ) , portal ( b ) and 3 min after injection delayed ( c ) acquisitions .
a well - defined , heterogeneous nodule with moderate enhancement on portal phase arising from the gastric fundus was found ( yellow arrows ) .
d microscopic studies performed after surgical removal of the lesion demonstrated high amount of mesenchymal fusiform cells combined with vascular structures .
the lesion showed well - defined contours and an expansive growth pattern pathology : pararectal imt .
axial and coronal reformations of contrast - enhanced ct on portal ( a , b ) and 8 min after injection delayed acquisitions ( c , d ) .
pararectal solid and well - defined mass with moderated peripheral enhancement adjacent to the rectum and left seminal vesicle was detected .
mesenchymal neoplasm composed of polygonal cells with clear cytoplasm and round normochromatic nuclei with abundant vessels and occasional scattered inflammatory cells was observed .
mixed within the neoplasm cells , there was a chronic inflammatory infiltrate of lymphoid cells .
there were no foci of necrosis or mitotic figures pathology : metastatic imt of the appendix . a 63-year - old man with antecedents of left hemicolectomy due to colon cancer .
a axial reformation of contrast - enhanced ct on portal phase acquired seven years after partial colectomy .
an appendicular , irregular , solid mass with slight enhancement was identified ( yellow arrow ) . due to its radiological features ,
b axial reformation of contrast - enhanced ct on portal phase performed 8 months later showed a significant growth of the appendicular mass with extension and infiltration of the adjacent small bowel loops .
c distant lymphadenopathy and liver metastases were present the differential diagnosis of these tumours includes gist , inflammatory fibroid polyp , smooth muscle neoplasm , peripheral nerve sheath tumour , solitary fibrous tumour , fibromatosis , the follicular dendritic cell sarcoma , lymphoma and adenocarcinomas . in most of these cases
imts of the gastrointestinal tract present a higher recurrence rate than in other locations of the body .
other treatments , such as steroids , non - steroidal anti - inflammatory drugs and thalidomide , have been used in these tumours .
radiotherapy may have a place as adjunctive therapy in local recurrence and incomplete surgical removal .
imts of the appendix are extremely rare , with few cases reported in the literature [ 9 , 33 , 34 ]
. chronic infections , antecedents of trauma or surgery have been proposed as possible aetiological factors .
extremely rare cases of imts of the appendix showing local aggressiveness and metastases have been reported   ( fig . 
many different aetiological factors have been proposed for mesenteric imts [ 37 , 38 ] , such as chronic infections , autoimmune diseases and trauma .
on contrast - enhanced ct they usually appear as solid masses with heterogeneous enhancement pattern and ill- or well - defined margins .
they are often associated with a general inflammatory response manifested with fever , weight loss and other symptoms that are related to the compressive effect of the tumour , such as abdominal pain and vomiting .
rapidly growing tumours or symptomatic ones needing treatment may follow from small tumours which are not encroaching any nearby structures .
different treatments have been proposed : non - steroidal anti - inflammatories , anti - oestrogens , chemotherapeutic agents and surgery .
surgery remains as a useful modality although quite a high local recurrence rate has been described for tumours [ 3 , 37 , 38 ] .
the symptoms that most often appear include pain , haematuria , dysuria or urinary tract obstruction .
the radiological features do not help to distinguish them from malignant neoplasms , such as rabdomyosarcomas ( fig . 
, fine - needle biopsy may fail to yield a sufficient volume of tumour tissue to achieve diagnosis.fig .
a axial and b coronal reformations of contrast - enhanced ct where an ill - defined and heterogeneous mass encompassing iliopsoas muscle and external iliac vessels , mimicking malignant sarcomatous neoplasm was observed .
proliferation of fibroblast with a diffuse infiltration of lymphocytes , eosinophils and macrophages were found .
the mass was well - defined and no signs of invasiveness were found pathology : imt of the iliopsoas muscle .
a axial and b coronal reformations of contrast - enhanced ct where an ill - defined and heterogeneous mass encompassing iliopsoas muscle and external iliac vessels , mimicking malignant sarcomatous neoplasm was observed .
proliferation of fibroblast with a diffuse infiltration of lymphocytes , eosinophils and macrophages were found . no mitotic figures or cellular atypia were present .
imts have been reported in various sites in the head and neck such as bucal space , maxillary sinus , nasal cavity , parotid gland , nasopharynx and larynx ( fig . 
1pathology : imt in the left supraglottic space ( arrow ) with paraglottic space involvement indicated by replacement of the paraglottic fat with soft tissue . a axial reformation of contrast - enhanced neck ct . a solid , well - defined ,
normal tissue was present in the peripheral zone ( * ) pathology : imt in the left supraglottic space ( arrow ) with paraglottic space involvement indicated by replacement of the paraglottic fat with soft tissue . a axial reformation of contrast - enhanced neck ct .
a solid , well - defined , little - enhancing nodule in the supraglottic larynx was observed ( yellow arrow ) .
b microscopic study obtained after surgical removal of the lesion . the sample showed proliferation of fusiform cells mixed with macrophages and giant multinucleated cells .
normal tissue was present in the peripheral zone ( * ) however , the orbit is the most common location of imts .
they account for approximately 10  % of orbital masses , being the third most common cause of orbital masses .
their aetiology is unknown , but they have been associated with inmunological disorders , different infections and history of trauma .
recently , they have been strongly associated with the igg4-related sclerosing systemic inflammatory disease   and with chronic infection by epstein - barr virus .
the clinical presentation and symptoms may vary with the location , extension and aggressiveness of the tumour .
patients with imts of the orbit can present local symptoms as pain , redness , oedema , proptosis , ptosis , oculomotor deficits , diplopia , lid swelling or mass - effect and systemic symptoms due to the general inflammatory disorders they are frequently associated with .
mri is superior to ct in the evaluation of inflammation of the nerves and muscles .
they usually appear as solid and heterogeneous enhancing masses , which can affect retro bulbar fat , cause bone destruction , and present intracranial extension . when they show low intensity on t2-weighted images prominent , fibrotic composition is present ( fig . 
a , b axial and coronal mr reformations of the same patient on t2-weighted sequences showed a well - delimited , hyperintense intraorbital mass , in the intraconal compartment , in the medial aspect .
c , d t1-weighted images demonstrated a hypointense , homogeneous , well - delimited mass with peripheral enhancement after gadolinium injection .
f microscopic sample obtained after surgery demonstrated an epithelial tumour composed of fusiform cells mixed with an extensive chronic inflammatory infiltrate of plasmatic cells , lymphocytes and macrophages . in the peripheral of the sample
a , b axial and coronal mr reformations of the same patient on t2-weighted sequences showed a well - delimited , hyperintense intraorbital mass , in the intraconal compartment , in the medial aspect .
c , d t1-weighted images demonstrated a hypointense , homogeneous , well - delimited mass with peripheral enhancement after gadolinium injection .
f microscopic sample obtained after surgery demonstrated an epithelial tumour composed of fusiform cells mixed with an extensive chronic inflammatory infiltrate of plasmatic cells , lymphocytes and macrophages . in the peripheral of the sample striated muscle cells
were also observed pathologically , imts of the head and neck consist of many fibroblastic cells , fibroblastic cells and inflammatory cells , which include plasma cells and eosinophils .
the differential diagnosis includes granulomatous diseases , primary infection , sarcoid , sjgren disease , primary and secondary tumours of the orbit , lymphoma and connective tissue diseases .
the administration of corticosteroids an inmunosupresors usually leads to a decrease of size of the mass but also radiotherapy or surgery may be indicated .
. they account for around the 50  % of benign pulmonary masses in children , representing only about 0.7  % of all tumours of the lung in general population . as in other organs
, they are also associated with immunological disorders   and chronic infections . sometimes , imts are also related with antecedents of lung surgery and they can arise in surgical lung scars .
common clinical characteristics include unspecific respiratory symptoms , such as cough , chest pain , dyspnea , haemoptysis and unspecific inflammatory symptoms as fever , malaise and weight loss .
they usually appear as solitary , well - circumscribed peripheral lung masses , with predominance for the lower lobes   ( fig . 
on ct with intravenous contrast , they present a variable heterogeneous or homogeneous degree of enhancement pattern [ 3 , 21 ] . it has been described an aggressive behaviour with invasion of the adjacent structures . on mri
because of their similar radiological appearance to malignant lung masses , biopsy is necessary to obtain the diagnosis.fig .
a 55-year - old man with a cough and haemoptysis.a axial reformation of non - contrast ct with mediastinum window .
two solid , ill - defined nodules in right lower lobe are observed ( yellow arrows ) .
b axial reformations with lung window of the same patient where the lung nodules are shown ( white arrows ) .
c partial lobectomy of the right lower lobe specimen . note the presence of the nodules ( * ) .
d microscopic study of the resected lung sample where fusiform cells with an associated inflammatory infiltrate of lymphocytes , plasmatic cells and histiocytes was found pathology : imt of the lung . a 55-year - old man with a cough and haemoptysis.a axial reformation of non - contrast ct with mediastinum window .
two solid , ill - defined nodules in right lower lobe are observed ( yellow arrows ) . note the air brocogram observed in the biggest mass .
b axial reformations with lung window of the same patient where the lung nodules are shown ( white arrows ) .
d microscopic study of the resected lung sample where fusiform cells with an associated inflammatory infiltrate of lymphocytes , plasmatic cells and histiocytes was found the treatment of choice of lung imts is surgery to exclude malignancy and to achieve the cure .
although spontaneous regression may occur , local expansion may cause significant morbidity and occasional death .
the prognosis after complete surgical resection is excellent , with a low rate of recurrence . in these cases ,
alternative treatments ( radiotherapy , corticoids or chemotherapy ) to surgery could be also used .
the most common presentation of epididymal ( fig .  4 ) and paratesticular imts is a lump in the scrotum.fig .
4pathology : imt of the epididymus . a 40-year - old man with a lump in the scrotum . a a hypoechoic
a diffuse infiltrate composed of fibroblastic and fusiform cells mixed with inflammatory cells ( mainly lymphocytes and macrophages ) was observed pathology : imt of the epididymus . a 40-year - old man with a lump in the scrotum . a a hypoechoic , well - delimited epididymal lesion in the right scrotum was detected .
a diffuse infiltrate composed of fibroblastic and fusiform cells mixed with inflammatory cells ( mainly lymphocytes and macrophages ) was observed in the evaluation of scrotal masses , us is the most accurate imaging technique , helping to distinguish intratesticular from extratesticular lesions and solid from cystic lesions .
on ct , they appear as well - defined , hypodense masses with little enhancement after intravenous contrast injection . in some cases ,
a 34-year - old man with no relevant medical history came to our hospital with a lump in the scrotum .
a us showed an isoechoic , solid , paratesticular nodule with fine calcifications ( yellow arrow ) .
b axial reformation of contrast - enhanced ct on portal phase demonstrated a well - delimited , heterogeneous , little - enhancing mass in the right scrotum .
d microscopic study of the lesion demonstrated a well - delimited lesion constituted of fibroblasts , lymphocytes and plasmatic cells with associated lymphoid follicle .
a 34-year - old man with no relevant medical history came to our hospital with a lump in the scrotum .
a us showed an isoechoic , solid , paratesticular nodule with fine calcifications ( yellow arrow ) .
b axial reformation of contrast - enhanced ct on portal phase demonstrated a well - delimited , heterogeneous , little - enhancing mass in the right scrotum .
d microscopic study of the lesion demonstrated a well - delimited lesion constituted of fibroblasts , lymphocytes and plasmatic cells with associated lymphoid follicle .
there was no evidence of adjacent testicle invasion surgical resection without orchiectomy is the ideal treatment , but in some cases the testicle must be removed due to the size of the mass or when the mass is attached to the testis .
imts of the penis are extremely rare . to our knowledge , no imts at this location have been reported .
we have recorded only one case in our institution ( fig .  6 ) .
on ct , this tumour appeared as a well - defined , little - enhancing and non - aggressive mass surrounding the penile urethra and the corpora cavernosa with no evidence of invasion of them.fig .
a 46-year - old man with a mass in the penis came to our hospital .
he related more than 6 years of slow growth of the mass with no suspicious associated symptoms .
c , d axial and coronal reformations of enhanced - ct after the injection of intravenous contrast on portal phase .
macroscopic view showed an heterogeneous aspect due to the mixture of tissues ( solid tumour , lipoid component and areas of haemorrhage ) .
f microscopic study confirmed a mesenchymal tumour composed of fusiform cells , some of them multinucleated , with round or elongate nucleus .
a 46-year - old man with a mass in the penis came to our hospital .
he related more than 6 years of slow growth of the mass with no suspicious associated symptoms .
c , d axial and coronal reformations of enhanced - ct after the injection of intravenous contrast on portal phase .
macroscopic view showed an heterogeneous aspect due to the mixture of tissues ( solid tumour , lipoid component and areas of haemorrhage ) .
f microscopic study confirmed a mesenchymal tumour composed of fusiform cells , some of them multinucleated , with round or elongate nucleus .
no mitotic figures were observed surgical treatment was performed due to the size and non - conclusive radiological features of the tumour .
hepatic imts constitute an extremely rare group of hepatic tumours , accounting only for the 0.7  % of all the hepatic lesions .
they have been associated with autoimmune diseases , immunological disorders and viral infections , such as igg4 disease , sclerosing cholangitis , crohns disease , hepatic viral infections   and epstein - barr virus .
on contrast - enhanced ct , they usually show heterogeneous or peripheral enhancement during the arterial phase . despite this ,
some of them present homogeneous enhancement during the arterial phase and washout during the delayed phase , which can lead to misdiagnosing them as hepatocarcinomas ( hccs )   ( fig .  7 ) . on mri , these lesions usually are t1 hypointense and t2 hyperintense with heterogeneous enhancement ( fig .  8) .
hepatobiliary contrast ( gadoxetate disodium , primovist ; bayer healthcare , leverkusen , germany ) could be of help to differentiate hcc from imts of the liver .
on the hepatobiliary phase , high signal intensity in the centre of the lesion has been described , suggesting a benign lesion.fig .
well - defined , hypointense lesion on t1-weighted images ( a ) which presented weak enhancement in the arterial phase ( b ) and wash - out on portal and equilibrium phases ( c- , d ) located in hepatic left lobe .
f the lesion demostrated an expansive chronic inflammatory infiltrate of plasmatic cells , lymphocytes and macrophages .
a abdominal ultrasound where a slightly hypoechoic , solid , heterogeneous mass arising in the left hepatic lobe was observed .
axial t1-weighted unenhanced ( b ) and contrast - enhanced mr images ( c , d ) showed an ill - defined with heterogeneous enhancement mass located in lateral hepatic segments .
mesenchymal tumour composed of fusiform cells , lymphocytes and lipid - filled macrophages can be observed .
normal hepatocytes with large and small fatty droplet change are also present pathology : imt of the liver .
well - defined , hypointense lesion on t1-weighted images ( a ) which presented weak enhancement in the arterial phase ( b ) and wash - out on portal and equilibrium phases ( c- , d ) located in hepatic left lobe .
e macroscopic view of partial hepatectomy obtained after surgical excision of the lesion . a solid , well - defined and yellowing appearance mass is showed .
f the lesion demostrated an expansive chronic inflammatory infiltrate of plasmatic cells , lymphocytes and macrophages .
a abdominal ultrasound where a slightly hypoechoic , solid , heterogeneous mass arising in the left hepatic lobe was observed .
axial t1-weighted unenhanced ( b ) and contrast - enhanced mr images ( c , d ) showed an ill - defined with heterogeneous enhancement mass located in lateral hepatic segments .
mesenchymal tumour composed of fusiform cells , lymphocytes and lipid - filled macrophages can be observed .
normal hepatocytes with large and small fatty droplet change are also present surgery is the most accepted treatment .
if there is a biopsy - proven diagnosis of imts that excludes malignancy , medical treatment with no steroidal anti - inflammatory drugs in patients with peripheral hepatic imts could be prescribed .
patients with spleen imts frequently associate unspecific symptoms as left upper quadrant or epigastric pain .
splenomegaly is common and some patients can present fever , anaemia and signs of hypersplenism .
different radiological imaging modalities have been proposed for their evaluation . on all of them ,
they are depicted as low - density masses in both non - enhanced and enhanced acquisitions ( fig . 
their typical enhancement pattern after gadolinium injection is as a low - intensity lesion in the early phase , which changes into a high - intensity one in the delayed phase .fig .
9pathology : imt of the spleen . a axial reformation of contrast - enhanced ct on portal phase .
prominent cellularity composed of an irregular , weakly basophil set of mioepithelial - fusiform cells .
numerous inflammatory cells ( plasmatic , lymphocytes and few neutrophils and eosinophils ) with isolated macrophages were also found .
no atypia or mitotic figures were present pathology : imt of the spleen . a axial reformation of contrast - enhanced ct on portal phase .
prominent cellularity composed of an irregular , weakly basophil set of mioepithelial - fusiform cells .
numerous inflammatory cells ( plasmatic , lymphocytes and few neutrophils and eosinophils ) with isolated macrophages were also found .
no atypia or mitotic figures were present the differential diagnosis includes splenic haemangioma and other primary splenic neoplasms such as lymphoma or splenic angiosarcoma . when a suspicious spleen mass is found , the treatment of choice is splenectomy due to the high risk of bleeding associated to splenic biopsy [ 8 , 31 ] .
they can arise anywhere , the stomach and small intestine being the most common locations [ 3 , 9 ] .
clinical symptoms may vary from none to abdominal pain , intestinal obstruction , dysphagia or anaemia , depending on the location and size of the mass .
contrast - enhanced ct is the imaging technique , which give us more information about of imts of the gastrointestinal tract .
they are usually found as hypodense , heterogeneous and well - delimited masses ( figs . 
axial reformation of contrast - enhanced ct on arterial ( a ) , portal ( b ) and 3 min after injection delayed ( c ) acquisitions .
a well - defined , heterogeneous nodule with moderate enhancement on portal phase arising from the gastric fundus was found ( yellow arrows ) .
d microscopic studies performed after surgical removal of the lesion demonstrated high amount of mesenchymal fusiform cells combined with vascular structures .
axial and coronal reformations of contrast - enhanced ct on portal ( a , b ) and 8 min after injection delayed acquisitions ( c , d ) .
pararectal solid and well - defined mass with moderated peripheral enhancement adjacent to the rectum and left seminal vesicle was detected .
e macroscopic view of the tumour after surgical resection . f histological sample obtained after biopsy .
mesenchymal neoplasm composed of polygonal cells with clear cytoplasm and round normochromatic nuclei with abundant vessels and occasional scattered inflammatory cells was observed .
mixed within the neoplasm cells , there was a chronic inflammatory infiltrate of lymphoid cells .
12pathology : metastatic imt of the appendix . a 63-year - old man with antecedents of left hemicolectomy due to colon cancer .
a axial reformation of contrast - enhanced ct on portal phase acquired seven years after partial colectomy .
an appendicular , irregular , solid mass with slight enhancement was identified ( yellow arrow ) . due to its radiological features ,
b axial reformation of contrast - enhanced ct on portal phase performed 8 months later showed a significant growth of the appendicular mass with extension and infiltration of the adjacent small bowel loops .
axial reformation of contrast - enhanced ct on arterial ( a ) , portal ( b ) and 3 min after injection delayed ( c ) acquisitions .
a well - defined , heterogeneous nodule with moderate enhancement on portal phase arising from the gastric fundus was found ( yellow arrows ) .
d microscopic studies performed after surgical removal of the lesion demonstrated high amount of mesenchymal fusiform cells combined with vascular structures .
the lesion showed well - defined contours and an expansive growth pattern pathology : pararectal imt .
axial and coronal reformations of contrast - enhanced ct on portal ( a , b ) and 8 min after injection delayed acquisitions ( c , d ) .
pararectal solid and well - defined mass with moderated peripheral enhancement adjacent to the rectum and left seminal vesicle was detected .
mesenchymal neoplasm composed of polygonal cells with clear cytoplasm and round normochromatic nuclei with abundant vessels and occasional scattered inflammatory cells was observed .
mixed within the neoplasm cells , there was a chronic inflammatory infiltrate of lymphoid cells .
there were no foci of necrosis or mitotic figures pathology : metastatic imt of the appendix . a 63-year - old man with antecedents of left hemicolectomy due to colon cancer .
a axial reformation of contrast - enhanced ct on portal phase acquired seven years after partial colectomy .
an appendicular , irregular , solid mass with slight enhancement was identified ( yellow arrow ) . due to its radiological features ,
b axial reformation of contrast - enhanced ct on portal phase performed 8 months later showed a significant growth of the appendicular mass with extension and infiltration of the adjacent small bowel loops .
c distant lymphadenopathy and liver metastases were present the differential diagnosis of these tumours includes gist , inflammatory fibroid polyp , smooth muscle neoplasm , peripheral nerve sheath tumour , solitary fibrous tumour , fibromatosis , the follicular dendritic cell sarcoma , lymphoma and adenocarcinomas . in
most of these cases imaging features are not enough to diagnose imts and biopsy or surgery are needed .
imts of the gastrointestinal tract present a higher recurrence rate than in other locations of the body .
other treatments , such as steroids , non - steroidal anti - inflammatory drugs and thalidomide , have been used in these tumours .
radiotherapy may have a place as adjunctive therapy in local recurrence and incomplete surgical removal .
imts of the appendix are extremely rare , with few cases reported in the literature [ 9 , 33 , 34 ] .
chronic infections , antecedents of trauma or surgery have been proposed as possible aetiological factors .
extremely rare cases of imts of the appendix showing local aggressiveness and metastases have been reported   ( fig . 
many different aetiological factors have been proposed for mesenteric imts [ 37 , 38 ] , such as chronic infections , autoimmune diseases and trauma .
on contrast - enhanced ct they usually appear as solid masses with heterogeneous enhancement pattern and ill- or well - defined margins .
they are often associated with a general inflammatory response manifested with fever , weight loss and other symptoms that are related to the compressive effect of the tumour , such as abdominal pain and vomiting .
rapidly growing tumours or symptomatic ones needing treatment may follow from small tumours which are not encroaching any nearby structures .
different treatments have been proposed : non - steroidal anti - inflammatories , anti - oestrogens , chemotherapeutic agents and surgery .
surgery remains as a useful modality although quite a high local recurrence rate has been described for tumours [ 3 , 37 , 38 ] .
the symptoms that most often appear include pain , haematuria , dysuria or urinary tract obstruction .
the radiological features do not help to distinguish them from malignant neoplasms , such as rabdomyosarcomas ( fig . 
, fine - needle biopsy may fail to yield a sufficient volume of tumour tissue to achieve diagnosis.fig .
a axial and b coronal reformations of contrast - enhanced ct where an ill - defined and heterogeneous mass encompassing iliopsoas muscle and external iliac vessels , mimicking malignant sarcomatous neoplasm was observed .
proliferation of fibroblast with a diffuse infiltration of lymphocytes , eosinophils and macrophages were found . no mitotic figures or cellular
the mass was well - defined and no signs of invasiveness were found pathology : imt of the iliopsoas muscle .
a axial and b coronal reformations of contrast - enhanced ct where an ill - defined and heterogeneous mass encompassing iliopsoas muscle and external iliac vessels , mimicking malignant sarcomatous neoplasm was observed .
proliferation of fibroblast with a diffuse infiltration of lymphocytes , eosinophils and macrophages were found . no mitotic figures or cellular
although imts in some organs are not uncommon , they are not usually included in the differential diagnosis of nodules and masses .
consequently , this is an underdiagnosed entity and only after an histological exam could definitive diagnosis be achieved .
it is fundamental for radiologists to know about the existence of imts , as they frequently have better treatment options and prognosis than the malignant neoplasms they are confused with .
 objectivesto present the most important characteristics of inflammatory myofibroblastic tumours ( imts ) arising in different locations of the body with histological correlation.methodsto review the symptoms and main radiological findings of imts . on ultrasonography ( us ) 
 , these tumours can appear as hypoechoic or hyperechoic masses and a variable doppler appearance with increased vascularity . 
 computed tomography ( ct ) and magnetic resonance ( mr ) are the most used imaging tools in their evaluation . on contrast - enhanced ct , imts can appear as homogeneous or heterogeneous lesions , with variable enhancement on delayed acquisitions due to fibrosis . these findings are also present on gadolinium contrast - enhanced mr . on t1-weighted and t2-weighted sequences , imts 
 usually show low signal intensity reflecting also the presence of fibrotic tissue.resultsto show the main clinical symptoms and radiological features of imts in different locations : head and neck , lung , genitourinary , hepatic , splenic , gastrointestinal tract , mesenteric , muskuloskeletal.conclusionsalthough imts in some organs are not uncommon , they are not usually included in the differential diagnosis of masses . 
 their radiological features suggest malignant neoplasms , whereas they are not . 
 consequently , this is an underdiagnosed entity and only after an histological exam could a definitive diagnosis be achieved.teaching points their radiological features suggest malignant neoplasms , whereas they are not ct and mr imaging are the most used tools in their evaluation imt is an underdiagnosed entity the definitive diagnosis is only after histological exam 
None
Introduction
Imaging techniques
IMTs in different locations of the body
Head and neck IMTs
Pulmonary IMTs
Genitourinary IMTs
Hepatic IMTs
Splenic IMTs
Gastrointestinal tract IMTs
Mesenteric IMTs
Musculoskeletal IMTs
Conclusions