Clinical features

•Very rare

•Usually solitary flesh colored papule/nodule up to 1.5 cmdiameter

•Head & neck

•F>M

•Middle aged or elderly

•Exceptional association with Cowden syndrome

•May arise in a nevus sebaceus

•Multiple/eruptive variant (infundibulomas)

Histological features

•Can be a non-specific component of a wide variety of other tumors including BCC, AK, desmoplastic trichilemmoma etc

•Can arise in a nevus sebaceus

•Characteristic fenestrated epithelial plate-like silhouette suspended below the epidermis

•Pale-staining epithelial cells with peripheral palisading

•Eosinophilic basement membrane

•No pleomorphism or mitotic activity

•BerEP4 –ve

•CK20 +ve Merkel cells

•Regarded by some authors as a variant of seborrheic keratosis