Atrichia with papular lesions - Electron microscopic observations of cystic lesions

Atrichia with papular lesions is a rare inherited skin disorder characteriz ed by congenital atrichia with numerous papules. We describe a 27-year-old woman with atrichia, who had numerous papules on her scalp, nape, and axill ae. Histologically, many keratinous cysts were seen in the middermis of a s kin specimen from the nape. Electron microscopy showed that the developing keratinocytes in the walls of some cysts were rich in glycogen granules and had epidermoid keratinization with formation of keratohyaline granules and that laminated bodies were formed before keratinization. Langerhans cells were often seen in the walls of the cysts. In addition, a broad glassy vitr eous layer surrounded the cyst wall. From these findings, it was suggested that the cystic lesions might have originated from immature or incomplete h air follicles. In particular, the structure of the cyst wall corresponded w ell to infundibular and/or isthmal portions of the outer root sheath of the hair follicle.