Case Reports : A Case of Trichoadenoma : Occurrence of a Rare Site and Immunohistochemical Staining Pattern of CD34

Trichoadenoma is a rare tumor with differentiation towards the infundibular portion of the pilosebaceous canal. Clinically, it is a nodular growth, usually on the face and buttock. Histologically, it is characterized by numerous horn cysts lined with squamous epithelium in the dermis. In this report, we describe a 44-year-old man who developed trichoadenoma on his right shin. Anti-CD34 antibody stained spindle-shaped cells in the stroma just adjacent to the peripheral layers of keratinous cysts and solid masses of squamous epithelial cells. To our knowledge, this is the first description of an occurrence of trichoadenoma in the lower leg and the first to use immunohistochemical staining to know the CD34 staining pattern.(Ann Dermatol 9:(2) 167-170, 1997).