Malignant pilomatrixoma arising on the previously irradiated face: case report and literature review

Malignant pilomatrixoma (also known as pilomatrix carcinoma) is a very rare malignant neoplasm derived from the hair matrix. These slow-growing malignancies of the skin are found in the lower dermis and subcutaneous fat layer. They can exhibit local aggressive behavior or distant metastasis. This malignancy can arise as a solitary lesion de novo or through transformation of a pilomatrixoma over a long period. There is no known distinct etiologic factor or predisposing condition for this kind of malignancy.

We present an interesting case of a 65-year-old man with a pilomatrix carcinoma arising on the previously irradiated face due to the malignant neoplasm of the parotid gland. This is the first report of a pilomatrix carcinoma that has developed on a region that has undergone radiotherapy for another malignancy.