Magnetic resonance imaging findings of proliferating trichilemmal tumor.

We report the magnetic resonance (MR) imaging findings of proliferative trichilemmal tumor (PTT), a rare benign tumor of the scalp. MR imaging showed a well-margined mass with isointense signal on T(1)-weighted images and heterogeneous mixed intensity signal on T(2)-weighted images After i.v. administration of contrast material, the mass showed significant enhancement, with small portions remaining unenhanced. It was considered that these findings reflected the pathological characteristics of PTT, which consists of solid lobules and cystic cavities.