Red flag in granular cell tumors: Role of a pathologist

Granular cell tumors (GCTs) are uncommon mesenchymal tumors of Schwann cell origin with malignant potential. A 50-year-old female presented with the complaints of swelling in right thigh since 1 year, associated with pain for 4 months. After clinical examination, imaging and histopathological examination diagnosis of malignant granular cell tumor (M-GCT)-Grade 1 (WHO grading of soft tissue tumors), stage-pT _2b N _x M _x was made. On immunohistochemistry tumor cells were positive for S-100 and Ki-67 expression was increased (>10%), confirming the histopathological diagnosis. M-GCTs though rare, are associated with local recurrence and metastasis. A thorough histopathological examination, grading and immunohistochemistry analysis is crucial for differentiation from benign soft tissue tumors. Fanburg-Smith et al. grading may aid in differentiating benign, atypical, and malignant variants. This case is reported for its rarity and to stress upon the importance of diagnosing malignancy in GCTs.