Concurrent Pilomatrix Carcinoma and Diffuse Large B-Cell Lymphoma.

Pilomatrix carcinoma is a rare cutaneous tumor derived from follicular matrix cells. It may arise de novo or from a malignant transformation of a pilomatrixoma. The latter process has been associated with impaired immune system surveillance of the host caused by UV radiation or the onset of an underlying malignant neoplasm. We report a case of a 58-year-old man presenting with a long-standing pilomatrix carcinoma on the inner right leg after 10 years of repeated curettage of the lesion, concurrent with a high-grade B-cell lymphoma on the same extremity. We describe a rare association which highlights the necessity of close follow-up of patients with long-standing malignant skin tumors.