HISTOPATHOLOGY AND IMMUNUOHISTOCHEMISTRY IN DAIGNOSIS OF SOFT TISSUE TUMORS

Abstract

Background: Soft tissue tumors defined as mesenchymal proliferation occur in the extra-skeletal non-epithelial tissues of the body, excluding the viscera, coverings of the brain, and lymphoreticular system.

The main objective of immunohistochemistry in soft tissue neoplasms, especially sarcomas, is to identify differentiation in the neoplastic cells.

OBJECTIVES: To study the histopathology of both benign and malignant Soft tissue tumors: i) To study the histopathological spectrum of soft tissue tumors in relation to age, gender, and anatomical site, and ii) Confirmation of the diagnosis by immunohistochemistry wherever needed.

STUDY DESIGN: Prospective study from Nov 2017 to April 2019.

PARTICIPANTS: 150 Cases were included in the study.

METHODS: Complete clinical details, examination findings, and radiological investigations were included. The excised tissue specimens were processed routinely and stained with Hematoxylin and Eosin; special stains like Immunohistochemistry was performed as required.

RESULTS: A total of 13933 surgical specimens were received in the department, of which soft tissue tumor constituted 150 (1.07%) cases. Of the total number of cases, 88 were males, and 62 were females, with male to female ratio of 1.41: 1. Of 150 cases, there were 101 benign tumors (70%) , 13 (10%) were in the intermediate group, and 36 (20%) were malignant tumors. The maximum number of cases were seen in the age group of 31-40 years (43 cases (28.66%)) . The most common benign tumor was a lipoma (31 cases) , followed by hemangioma (27 cases) . The most common malignant tumor was liposarcoma (8 cases) , followed by rhabdomyosarcoma (7 cases) . IHC was done in 36 malignant tumors, 13 intermediate category tumors, and 10 benign cases. A definitive diagnosis was reached in 33/36 malignant, 7/13 intermediate, and 9/10 benign tumors. Thus, IHC played a significant role in making the diagnosis and determining tumor Differentiation.

CONCLUSION AND IMPLICATION: Our study highlights the importance of the affected age group, gender predilection, location, size, histopathology, and IHC features in diagnosing STTs. STTs located superficially in young males were more likely benign, while larger tumors located deep in the lower extremity, abdomen retroperitoneum, and mediastinum in older patients had high or intermediate malignant potential. FNCLCC grading helped in prognostication of malignant STTs, and IHC helped diagnose cases that shared histopathological features with other sarcomas and carcinomas. Hence, the right histopathological expertise with a custom panel of IHC markers and cytogenetic and molecular studies may be needed to diagnose these tumors accurately.