Proximal-type epithelioid sarcoma: A clinicopathological analysis of 4 cases

Objective: To investigate the pathological charcateristics,clinical and differential dignosis of proximal-type epthelioid sarcoma.Methods: The pathologic and immunophenotypic features of 4 cases of proximal-type epithelioid sarcoma were studied and all the cases were followed up.Results: Three of the patients were female and 1 was male.The age of the patients ranged from 33 to 58.The epithelioid sarcoma grew on the perineal region in two,on the chest wall in one and on the back in one.The tumors were painless subcutaneous firm growing solitary nodules.The tumor cells were round or ovoid,containing eosinophilic cytoplasm.The nucleus was located on one-side with obvious nucleoli.Rhabdoid features were frequently observed,seldom resulting in a granuloma-like alteration.The tumors stained positively for vimentin（4/4）,CK（4/4）,CD34（2/4）,EMA（1/4）,while negatively for MyoD1,S-100 Protein,SMA,HMB-45,and desmin.Two patients died after eight months since presentation,one patient was found liver metastasis after four months and died after twelve months,and one patient was still alive after fourteen months.Conclusions: The histopathological characteristics of proximal-type epithelioid sarcoma are as follows:the tumor cells show diffuse and densely eosinophilic cytoplasm,enlarged vesicular nuclei and prominent nucleoli.Rhabdoid features are frequently observed.All the tumor cells express vimentin and CK.The tumor cells express CD34 in half of the cases and express EMA in part of the cases.More attention should be paid to differentiate this tumor from other benign and malignant tumors exhibiting epithelioid features.The biological behaviour of proximal-type epithelioid sarcoma is highly maliganance.