Background: Soft tissue tumors (STTs) are a complex group of neoplasms and composed of nonepithelial supportive connective tissue. They are rare neoplasms, comprising ≤ 2% of cases. Due to variable origin and overlapping histopathological features, they pose a great diagnostic challenge to histopathologists. Aim: To analyze the relative frequency of STTs in Rohilkhand region according to their nature and demographic profile and also to discuss the role of immunohistochemistry (IHC) in diagnosing and classification of STTs. Materials and Methods: The study included a total of 240 cases of STTs diagnosed at pathology department for a period of 2 years, at a tertiary care teaching hospital of Rohilkhand region. On H&E sections, tumors were classified on the basis of their origin according to WHO classification 2013. Sections were also subjected to IHC analysis using different antibodies, where indicated. Result: Out of the total 240 cases, 214 (89.2%) cases were benign, 8 (3.3%) intermediate and 18 (7.5%) malignant. Incidence of both benign and malignant STTs was more common in males. The peak incidence of benign STTs was observed in the age groups of 21-40yrs and that of malignant tumors in 41–60 yrs. Lipoma was the commonest benign STT (46.7%), while tumors of fibroblastic origin were most common (33.3%) among the malignant category. Few common benign tumors were also identified at rare sites. Out of 18 malignant cases, in 2 (11.1%) cases, no definite opinion could be obtained and were classified as spindle cell sarcomas. Conclusion: Diagnosis of STTs require uses of special stains, immunohistochemistry and molecular methods in addition to the routine microscopic examination of H & E stained slides due to the morphologic similarities with each other and also with carcinomas.

Keywords: Carcinomas; Hematoxylin and Eosin; Immuno-histochemistry; Sarcomas; Soft tissue; Tumors.