A 13-year-old white girl was admitted with pachyonychia congenita, Kumer and Loos type 1. In addition to all nails being distally elevated, plantar keratoses and bullae, and a scalloped tongue, the patient also had keratotic papules on the elbows and knees. A cornoid lamella was identified in the histologic examination of keratotic papule. The cornoid lamella, widely regarded as pathognomonic for porokeratosis (Mibeli) and its variants, may not be specific. This histologic marker should be sought in other localized disorders of keratinization.