actinomycosis , a rare chronic granulomatous infection induced by actinomyces species , colonizes the mouth , colon , and vagina ( 1 ) . mucosal disruption may lead to infection at virtually any anatomic site of immunocompromised body , such as head and neck , chest , abdomen , and pelvis region . in literature reports , about 50% of all cases appear in the head and neck region , with relatively rare appearance at other sites ( 2 ) .
f - fluorodeoxyglucose ( fdg ) is a highly sensitive but not specific radiotracer that can accumulate at various inflammation and infection sites . only a few cases of actinomycosis appearance on f - fdg positron emission tomography / computed tomography ( pet / ct ) have been documented recenlty ( 23456 ) . here , we describe a rare appearance of pulmonary actinomycosis with intrapulmonary disseminated distribution and abscess formation on f - fdg pet / ct .
we found that the involved bones demonstrated increased focal uptake of radiotracer on mtc - methylene diphosphonate ( mdp ) bone scintigraphy , which has not been reported to the best of our knowledge .
a 41-year - old man was admitted to our hospital with complaints of cough for 8 months .
in addition , he had right thoracodorsal and shoulder discomfort as well as wrist swelling pain for 4 months . physical examination found a palpable abscess at both right upper backside and right wrist . blood routine examination and serum tumor marker analysis revealed no abnormality .
a chest ct scan revealed a 7.8  5.0 cm lung mass in the right upper lobe with spiculated margins and irregular chest wall infiltration , suggesting peripheral lung carcinoma .
subsequently , a tc - mdp whole bone scintigraphy was performed to determine whether there were bone metastasis .
1a , posterior ) showed that the uptake of radiotracer was increased at the right third and fourth posterior ribs ( small black arrows ) as well as right multiple carpal bones ( large black arrow ) . regional chest and right wrist ( fig .
1b : b1 , single photon emission computerized tomography [ spect ] ; b2 , ct ; b3 , spect / ct fusion ) tomography imaging examinations found no osseous abnormality .
the patient underwent f - fdg pet / ct for further evaluation since this imaging method had improved sensitivity compared to tc - mdp bone scintigraphy .
1d : d1 , pet ; d2 , ct ; d3 , pet / ct fusion ; fig .
1i , sagittal ) demonstrated a 7.8  5.0 cm mass in the upper lobe of the right lung with soft - tissue density and spiculated margins similar to results of the previous ct scan .
the mass had intense f - fdg accumulation with maximal standardized uptake value ( suvmax ) of 13.3 .
the infiltrative mass extended to adjacent chest wall , thoracodorsal muscle , and subcutaneous dermal tissues .
the soft tissues at the right upper backside was swelling with a high activity ( suvmax = 9.2 ) . additionally , some opaque mottled shadows were distributed in multiple lobes of the right lung and the inferior lobe of the left lung ( fig .
1e2 , f2 , ct ; fig . 1e3 , f3 , pet / ct fusion ) .
a ct - guided lung puncture biopsy was implemented to confirm the nature of the pulmonary mass .
several days later , 4 - 5 ml yellowish pus was leaked out of the previous puncture pore .
a little pus was collected by squeezing the puncture pinhole after sterilization . in the meantime , 0.5
finally , the patient received treatment with intravenous antibiotics ( piperacillin - sulbactam combined with levofloxacin ) followed by oral antibiotics ( cefuroxime combined with levofloxacin ) for 14 days .
actinomycosis is a rare , chronic , and slowly progressive bacterial infection caused by several members of actinomyces . among six pathogenic species of actinomyces spp .
, actinomyces israelii is the most common human pathogen . in our case , a less common species ( actinomyces odontolyticus ) was found .
actinomycosis induces suppurative and granulomatous inflammation characterized by swelling with suppuration , sinus tract formation , and purulent discharge containing yellowish sulfur granules in severe cases .
although it is usually involved in oral and cervicofacial infections , other sites of immunocompromised body can be infected .
it is mainly caused by aspiration of oropharyngeal or gastrointestinal secretions into the respiratory tract ( 7 ) .
the most common clinical symptoms of pulmonary actinomycosis are chest pain , productive cough , and dyspnea .
these non - specific clinical presentations make pulmonary actinomycosis difficult to be diagnosed , often leading to misdiagnosis of malignancy rather than an infective disease ( 7 ) .  
only a few authors have recently reported pulmonary actinomycosis appearance on f - fdg pet / ct ( 4891011 ) .
because there is not much difference in pet / ct findings between actinomycosis and malignancy , utilization of pet / ct to rule out malignancy seems unnecessary .
therefore , pulmonary actinomycosis should be kept in mind for differential diagnosis of cases with intensive activity on f - fdg pet / ct .
microbiological and pathological examinations with demonstration of actinomyces are indispensable for correct diagnosis of actinomycosis . in our case ,
ct - guided lung puncture biopsy was implemented and abscesses were punctured to culture the actual bacteria . to avoid contaminations with other external bacteria
, the specimen should be collected prior to antimicrobial therapy and carefully transported to the laboratory in anaerobic media .
in addition , histopathologic finding of yellowish sulfur granules within pus is often necessary for differential diagnosis of actinomycosis ( 12 ) . regarding treatment options ,
intravenous administration of penicillin should be given followed by oral penicillin or amoxicillin ( 13 ) . in cases of penicillin allergy or resistance , ceftriaxone ,
hyperbaric oxygen therapy may be used as an adjunct to conventional therapy when the disease process is refractory to antibiotics .
 here we report a case of 41-year - old man with a soft tissue density mass at right upper lung and palpable abscesses at right upper backside and right wrist . 
 18f - fluorodeoxyglucose positron emission tomography / computed tomography demonstrated a 7.8  5.0 cm mass with soft - tissue density in the upper lobe of the right lung with high metabolic activity . 
 the infiltrative mass extended to adjacent chest wall soft tissue . 
 final diagnosis of pulmonary actinomycosis with multiple abscesses was made . 
 the patient responded well to antibiotics treatment . 
INTRODUCTION
CASE REPORT
DISCUSSION