Proliferating trichilemmal tumor in the chest wall: report of a rare case.

Proliferating trichilemmal tumor (PTT) is an uncommon, usually benign lesion that usually arises on the scalp of elderly women. The lesion bears close morphologic resemblance to squamous cell carcinoma at the microscopic level, making correct histologic diagnosis extremely important. We present a case of PTT occurring on the chest wall of a 75-years-old man to highlight the significance of recognizing this unusual tumor at an uncommon location and discuss points of differentiation from squamous cell carcinoma.