Soft Tissue Tumours with Epithelioid Morphoogy

Background: To study the morphological findings of soft tissue sarcomas with epithelioid morphology and their distribution with respect to the age, gender and location. Methods: In this descriptive study, soft tissue sarcomas (n=100) with epithelioid morphology were evaluated by two histopathologists Cinical and morphological features like age, gender, site and type of tumor were quantified and documented. Epithelioid Morphology was defined as cells with polygonal to polyhedral shape, abundant cytoplasm and round nuclei .All cases were diagnosed with help of a panel of immunohistochemical (IHC) stains, i.e., CK ,EMA, Desmin, S100, CD31, CD34, INI-1, CD99 and TFE3 in conjunction with clinical history and morphology. lCA and HMB45 IHC stains were also utilized to rule out the possibility of a lymphoproliferative disorder and melanoma. Results: Mean age of presentation was 36 years, with patients ranging in age from 1 to 80 years. There were n=37 females as compared to n=44 males. Most common site was thigh (n=21) followed by arm (n=13), head and neck region (n=5) and inguinal region (n=4).Epithelioid sarcoma (n=29) was the most common soft tissue sarcoma in our study followed by sclerosing epithelioid fibrosarcoma (n=10), alveolar soft part sarcoma (n=9), biphasic synovial sarcoma and epithelioid angiosarcoma (n=8), epithelioid malignant peripheral nerve sheath tumours (MPNST) (n=7), epithelioid hemangioendothelioma, undifferentiated epithelioid sarcoma, epithelioid angiomyolipoma and epithelioid leiomyosarcoma(n=6). rare tumors included in the study were 2 cases of epithelioid rhabdomyosarcoma and one case each of pseudomyogenic hemangioendothelioma, malignant rhabdoid tumor and dedifferentiated liposarcoma with rhabdoid features. Conclusion: Soft tissue sarcomas with epithelioid morphology require careful morphological and immunohistochemical evaluation to differentiate them from carcinomas, lymphomas and melanoma because of the differences in their clinical management and prognosis. Introduction Soft tissue sarcomas constitute 1% of all malignant neoplasms. Epithelioid morphology, a defining feature of most carcinomas and melanomas characterizes many of these soft tissue tumors, and therefore knowledge of these tumors is imperative to avoid misdiagnosis. Soft tissue sarcomas represent a heterogeneous group of rare malignant neoplasms. These tumors account for almost 1% of all adult solid malignancies and about 20% of pediatric tumors.1Sarcomas can be divided into three broad categories based on their light microscopic appearance on H&E. These categories include the spindle cell sarcomas, round cell sarcomas and sarcomas with epithelioid morphology.Epithelioid morphology can be defined as polygonal to polyhederal cells with abundant cytoplasm, round to oval nuclei and distinct nucleoli. Epithelioid morphology literally meaning epithelial like is characteristic of carcinomas, however it can be seen in almost all tumor lineages especially melanomas. Soft tissue sarcomas with epithelioid morphology therefore present a unique challenge to the pathologist who has to differentiate it from carcinomas, melanomas and other soft tissue sarcomas of similar morphology.2,3 Sarcomas known to display epitheliod morphology include Epithelioid Sarcoma,epithelioid Malignant Peripheral Nerve Sheath Tumor, epithelioid Angiosarcoma, sclerosing epithelioid fibrosarcoma, Pseudomyogenic Hemangioendothelioma, Malignant Extra renal Rhabdoid tumor , Synovial Sarcoma, Epithelioid Rhabdomyosarcoma, Epithelioid Leiomyosarcoma and Myxofibrosarcoma.3,4,5 A thorough knowledge of these entities and use of immunohistochemical stains enables us to make definite diagnosis in majority of these cases. Patients and Methods Histology slides of the 100 cases of soft tissue sarcomas with epithelioid morphology were evaluated by two histopathologists with special interest in soft tissue pathology. Epithelioid Morphology was provisionally defined as cells with polygonal to polyhedral shape, abundant cytoplasm and round nuclei. Soft tissue Journal of Rawalpindi Medical College (JRMC); 2017;21(1): 37-41 38 sarcomas with rhabdoid features were also included in the study. The cases were selected solely on the basis of morphology. Clinical and morphological features like age, gender and site were assessed and documented. Cases with poor fixation, history of radiation therapy or carcinosarcomas were excluded from this study. All of the reported cases were diagnosed with help of a panel of immunohistochemical (IHC) stains; AE1/AE3, EMA, Desmin, CD31, CD34, INI-1, CD99 and TFE3 in conjunction with clinical history and morphology. LCA and HMB45 IHC stains were also utilized to rule out the possibility of a lymphoproliferative disorder