Small cell extraskeletal osteosarcoma: a rare case report.

Extraskeletal osteosarcoma is a rare malignant mesenchymal neoplasm and its small cell variant is one among the rarest variant. This article describes a 60-year-old woman presenting with a large, lobulated, painful mass in left thigh with associated history of trauma since 18 months. Her magnetic resonance imaging showed a variegated mixed intensity lesion with associated cystic degeneration, necrosis and matrix arborizing nearby muscles. Fine needle aspiration cytology showed a small cell lesion with very scant osteoid. Tumor was excised and histopathological diagnosis was small cell osteosarcoma involving adjacent muscles and fat with sparing of lymph nodes. The aim of this article is to present the clinical, radiological, cyto-histological and immunohistochemical features of this extremely rare lesion.