INI Expressing Epithelioid Sarcoma with Osteoclastic Giant Cells in a Child: A Case Report with Summary of Prior Published Cases

ABSTRACTBackground: Epithelioid sarcoma is a heterogeneous tumor with 2 subtypes, classic and proximal. The proximal variant is more aggressive and occurs in proximal location in young adults. Case Report: We present a proximal epithelioid sarcoma in the leg of an 8 year old girl with rhabdoid morphology and scattered osteoclastic giant cells. Nuclear INI-1 was retained. Despite wide local excision, local recurrence occurred at 8 months. Following re-excision, she developed a chest wall metastasis after 9 months. Conclusion: Epithelioid sarcoma, proximal type with osteoclastic giant cells in the pediatric age group has not been reported previously and should be considered in the differential diagnoses of tumors with epithelioid cell morphology and scattered osteoclastic giant cells. Retained INI expression helped to differentiate this tumor from malignant rhabdoid tumor.