Undifferentiated Pleomorphic Sarcoma of a Chronic Burn Scar of the Knee With Lymph Node Metastasis.

Malignant transformation of chronic burn scars are usually toward cutaneous lineages, including squamous cell carcinoma, basal cell carcinoma, and malignant melanoma. Sarcomas are less common. Undifferentiated pleomorphic sarcoma(UPS) is a subtype of soft tissue sarcoma with storiform-pleomorphic cells of uncertain origin, and has sparingly been reported to arise from burn scars. The majority are localized lesions probably due to the spatial distance of mesenchymal cells from the epithelium. The authors describe a rare case of UPS of the chronic burn scar of his knee with ipsilateral femoral and external iliac lymph node metastasis.