Primary subcutaneous leiomyosarcoma (LMSs) are uncommon of all soft tissue malignancies. Its frequency is about 1% to 2%, with a predilection for middle age, and found more frequently in the lower extremity. They can be of two types according to its primary site of origin: deep subcutaneous and superficial cutaneous. The physical appearance of this tumour resembles more with benign condition and can easily be mistaken for nonmalignant condition. Hence, it is important to diagnose it correctly and it is important to differentiate it from other spindle cell neoplasm.
A case of giant subcutaneous leiomyosarcoma is presented here which was found around knee in lower extremity. The diagnosis was suspected by histopathology and confirmed by immunohistochemistry.