A rare benign tumor showing differentiation towards the infundibular portion of the pilosebaceous canal. Some authors postulate that it occupies a place miday between trichoepithelioma & trichofolliculoma.

Clinical features

•Presents as a usually solitary, soft to firm, yellowish or pink nodule or plaque measuring up to 0.5-1.5 cm in diameter & most often affecting adults (mean 43 years)

•M=F

•Predilection for face & buttocks but may present elsewhere (neck, arm, thigh, shoulder, eyelid)

•Rare giant variants

•Rarely congenital or childhood

•Verrucous variant

Histological features

•Keratocysts showing infundibular keratinization i.e.with a granular cell layer

•Solid epithelial islands

•Fibrovascular stroma

•In verrucous trichoadenoma, the cysts may contain vellus hairs

•Merkel cells can be identified with CK20

.BerEP4 & androgen receptor -ve