Histopathological spectrum of soft-tissue tumors with immunohistochemistry correlation and FNCLCC grading: A North Indian Experience Hena Paul Singh, Sumit Grover, Bhavna Garg, Neena Sood Nigerian Medical Journal 2017 58(5):149-155 Introduction: Soft tissue tumors (STT) are mesenchymal neoplasms with a diverse spectrum and overlapping clinical, radiological and histological features. Histopathology and immunohistochemistry (IHC) are essential to make a diagnosis. Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) Sarcoma Group grading system based on tumour differentiation, mitotic rate and necrosis helps in predicting the tumour progression and treatment response. Aims: The goal of this study was to analyze the incidence, histological spectrum and IHC features of STTs and to grade sarcomas according to FNCLCC grading system. Material and Methods: This is a four year study conducted in the Department of Pathology of a tertiary care centre from July 2009 to June 2013. All histopathologically diagnosed STTs were evaluated for gross and microscopic appearance. IHC was done wherever needed and clinical correlation was attempted. Sarcomas were graded according to FNCLCC grading system. Results: Of the total 270 cases studied, benign, intermediate and malignant STTs were 67.0%, 7.0% and 25.9% respectively. Adipocytic, vascular and peripheral nerve sheath tumors (PNST) formed the bulk of overall STTs (34.1%, 18.5% and 11.1% respectively). Sarcomas not otherwise specified were found to be the most common soft-tissue sarcomas followed by smooth muscle sarcomas and tumors with uncertain differentiation (11.5%, 4.1%, and 3.3%, respectively). Benign STTs were seen two decades earlier and were superficial in location as compared to sarcomas. On FNCLCC grading, grade 3 soft tissue sarcomas were slightly higher in number than grade 2 (27 vs 24). On IHC a definitive diagnosis was reached in 33 malignant, all intermediate and nine benign cases. Conclusion: The incidence of intermediate and malignant STTs is increasing due to early detection and better diagnosis by ancillary techniques like IHC. FNCLCC grading helps to prognosticate the malignant STTs thus guiding further plan of action while in some tumors like MPNST and Angiosarcoma it has no prognostic significance.