Metastatic malignant fibrous histiocytoma mimicking keratoacanthoma

Malignant fibrous histiocytoma (MFH) has been considered to be the most common malignant soft tissue tumor of middle and late adulthood. This tumor is usually a skin-colored subcutaneous nodule. It metastasizes to the lung, lymph node, bone and liver. Metastasis to the skin is very rare. We present a case of a 69-year-old man who presented with an asymptomatic dome-shaped large nodule with central umbilical ulceration on his scalp that had grown abruptly over 3 months. The lesion clinically mimicked keratoacanthoma. Biopsy of the nodule was done to differentiate keratoacanthoma from MFH confirmed the latter. The result of biopsy was MFH. Diagnosis was MFH of unknown primary tumor origin. We report a case of metastatic MFH mimicking keratoacanthoma.