RESUMEN
Trichoadenoma is a rare cutaneous tumor that was first described by Nikolowski in 1958. It usually occurs as a single tumor on the face and its size varies from 3 to 50mm in diameter. It may arise any time during adult life. This tumor is less mature than trichofolliculoma and more differentiated than trichoepithelioma, and it is considered as a benign tumor with differentiation toward the infundibular portion of the pilosebaceous canal. In this report, we describe a 61-year-old women who developed trichoadenoma on the left shoulder of 3 years duration. The lesion was asymptomatic and had grown slowly. Histopathological findings showed numurous horn cysts with central keratinous material and solid tumor islands reaching to the deep dermis. Immunohistochemical studies showed negative findings for eccrine differentiation.