mucinous cystic tumors of the ovary rarely contain one or more solid mural nodules in which the histological features differ markedly from the background of benign , borderline or malignant mucinous neoplasms .
four varieties of mural nodules have been described , including true sarcomas , sarcoma - like mural nodules ( slmn ) , foci of anaplastic carcinoma and mixed type .
slmn stend to occur in younger women and are characterized by smaller size , sharp demarcation , a heterogeneous cell population , and no serious impact on the prognosis .
it should be differentiated from true sarcomatous mural nodules and foci of anaplastic carcinoma with areas of sarcomatoid differentiation since both of these lesions carry a graver prognosis .
we report a very rare case of slmn in a borderline mucinous tumor of the ovary .
a 30-year - old unmarried female patient presented with progressive abdominal enlargement for last 7 months .
she also complained of mild lower abdominal pain and discomfort for last 2 and half months .
a cystic swelling of about 18 - 20 weeks size reaching just below the level of umbilicus was felt on physical examination .
ultrasonography revealed a left ovarian cystic space - occupying lesion(sol ) of 12 cm  9.6-cm size with internal echogenicity and septations .
grossly the cystic ovarian mass [ figure 1a ] measured 13.8 cm  12 cm  8 cm .
an elevated firm , well - definednodular area measuring 4.8 cm  3.6 cm  2.5 cm was noticed on the inner surface of the largest locule .
microscopic examination displayed the histopathological features of a borderline mucinous tumor showing complex cribriform architecture with mild to moderate cellular atypia along with an adjacent circumscribed nodular area [ figure 1b and d ] .
however , no recognizable glandular structures infiltrating into the deeper part of the nodule were identified . the nodular area was predominantly composed of pleomorphic spindle cells with hyperchromatic nuclei and occasional prominent nucleoli arranged in a vaguely fascicular pattern .
the pleomorphic cells focally demonstrated smooth muscle and rhabdomyoblastic differentiation [ figure 2a and b ] .
frequent mitotic figures including atypical forms admixed with histiocytes and inflammatory cells especially eosinophils were noticed .
immunohistochemistry for cytokeratin was focally positive and vimentin was diffusely positive in the pleomorphic spindle cells of the nodule .
overall , the histopathogical features of the nodule closely mimicked that of a sarcoma except the presence of circumscription and absence of vascular invasion .
true sarcoma , atypical inflammatory myofibroblastic tumor , carcinosarcoma were considered as differential diagnoses . however , considering the circumscription of the nodule in macroscopy as well as in microscopy along with corroborative histopathological and immunohistochemical findings , the diagnosis of a borderline mucinous tumor with slmn was made .
( a ) mucinous cystic neoplasm of ovary with mural nodule ( b ) a well - circumscribed slmn alongwith borderline mucinous tumor ( h and e , 100 ) ( c ) a cellular well - demarcated nodular area of slmn ( h and e , 100 ) ( d ) complex atypical cribriform glands of borderline mucinous neoplasm ( h and e , 400 ) ( a ) photomicrograph showing prominent mitotic figures and smooth muscle differentiation in slmn ( h and e , 400 ) ( b ) rhabdomyoblastic differentiation in slmn ( h and e , 400 ) ( c ) photomicrograph showing coagulative necrosis in slmn ( h and e , 400 ) ( d ) atypical mucinous glands showing strong cytokeratin positivity and spindle cells of the nodule in the background displaying focal and weak cytokeratin positivity ( h and e , 100 )
in 1979 , prat and scully reported 14 cases of slmns , seven of them from the previous literature , and pointed outtheir favorable clinical behavior .
they described three types of morphology in slmns namely pleomorphic and epulis type , pleomorphic and spindle cell type and giant cell - histiocytic type .
sarcomatous nodules can exhibit a variety of patterns , including fibrosarcoma , rhabdomyosarcoma , and undifferentiated sarcoma .
mixed nodules may feature carcinosarcoma or a mixed anaplastic carcinoma and sarcoma - like nodule .
the present case displayed the morphology similar to the pleomorphic and spindle cell type with areas of smooth muscle and rhabdomyoblastic differentiation .
in contrast to slmns , the sarcomatous nodules and foci of anaplastic carcinoma which can also present as mural nodule , tend to occur in older patients and are characterized by larger size , poor circumscription , a monotonous spindle cell population in the former , evidence of carcinomatous differentiation in the latter , and aggressive behavior .
anaplastic carcinomatous nodules generally have spindled and rhabdoid cells with unequivocal cytologic features of a high - grade malignancy , and are associated with intraepithelial or invasive mucinous carcinoma in 72% of cases .
atypical inflammatory myofibroblastic tumors may resemble slmns possibly due toa florid reaction to intramural hemorrhage or spilling of mucinous material in cystic ovarian tumors .
in contrast to slmns that occur in association with an epithelial tumor , inflammatory myofibroblastic tumors have a predilection for relatively younger patients , appear de novo , and are larger and less well circumscribed .
although various hypotheses have been proposed to explain the histogenesis of the slmns , it probably represents a reactive and self - limited phenomenon within a neoplasia .
slmns usually strongly express vimentinand focally or weakly express cytokeratin , similar to true sarcomas yet distinct from anaplastic carcinomas that usually have strong / diffuse cytokeratin expression .
finally the age of the patient , well circumscription of the nodule and lack of vascular invasion were the only parameters that led us to the correct diagnosis .
the outcome of mucinous tumors with slmns is the same as the corresponding category of mucinous tumors without the nodule . but slmns should be regarded with caution as their histologic appearance is worrisome and clinical follow - up data are very limited .
hence , careful and meticulous examination of this rare lesion within a mucinous cystic tumor is essential for reassuring the patient of a favorable clinical outcome and for excluding the similar looking aggressive lesions having poorer outcome .
 sarcoma - like mural nodule ( slmn ) is a very uncommon and misleading benign entity which may be associated with benign , borderline or malignant mucinous neoplasm of the ovary . 
 it should be distinguished from other malignant mural nodules with sarcoma , carcinosarcoma or anaplastic carcinoma for proper management . 
 we report a rare case of slmn in a borderline mucinous tumor of the ovary in a 30-year - old lady . in spite of having confusing 
 histopathological features the final diagnosis was made depending on the younger age of the patient , well circumscription of the nodule , absence of vascular invasion and immunohistochemical profile . 
INTRODUCTION
CASE REPORT
DISCUSSION