Clinicopathologic Study of 90 Cases of Trichofolliculoma

In a clinicopathologic study of 90 cases of trichofolliculoma, a rare benign tumor with follicular differentiation, researchers found that the condition predominantly affected middle-aged adults with a mean age of 45.1 years and had a sex ratio of 54 males to 34 females. The tumors were primarily located on the face, particularly the nose (37.5%), malar/cheek area (13.6%), and ear (12.5%). Clinically, trichofolliculomas presented as papules or nodules with an average diameter of 7 mm, and only a minority showed central hairs or a central crater. Histopathologically, the tumors were characterized by a central sinus, vellus hairs, and multiple immature and mature follicular structures, with sebaceous glands present in 41% of cases. Immunohistochemical staining revealed strong expression of CK17, PHLDA1, and BerEP4, as well as androgen receptors in the stroma, suggesting a stimulation of follicular induction by unknown factors. The study concluded that trichofolliculoma is a distinct clinicopathologic entity that does not belong to a spectrum of lesions and is often misdiagnosed clinically, with histopathology being crucial for diagnosis.