Hypokeratosis, circumscribed acral L98.9

Controversial, apparently congenital, very rare, eminently chronic, solitary epidermal differentiation disorder of the skin with the following clinical characteristics: atrophic, circumscripter (sharply defined, as if punched out), 0.2-3.0 cm large, less symptomatic red spot, which occurs predominantly on the palmar and less frequently on the plantar skin of the groin.

Unexplained; apparently a genetically induced circumscript keratinization defect with consecutive loss of keratinocyte adhesiveness occurs.

Predominantly the ball of the thumb, but also other parts of the palm and, more rarely, the sole of the foot.

Circumscripter, like punched out appearing thinned out orthokeratotic corneal layer. Regular-looking epidermis with a slightly thinned str. granulosum; low superficial, non-specific dermal infiltrate. No cornoid lamella, no cell atypia.

1. Erkek E et al (2014) Circumscribed acral hypokeratosis: a report of 2 cases and a brief review of the literature. Cutis 93: 97-101
2. Nguyen JV et al (2013) Dermatopathology diagnosis. Circumscribed acral hypokeratosis. Cutis 91:19-20
3. Obermoser G, Zelger B (2003) "Multifocal" circumscribed palmar hypokeratosis: malformation or not? J Am Acad Dermatol 49: 1197-1198
4. Pérez A et al (2002) Circumscribed palmar or plantar hypokeratosis: a distinctive epidermal malformation of the palms and soles. J Am Acad Dermatol 47: 1197
5. Rutten A et al (2004) Circumscribed acral hypokeratosis. dermatologist 55: 1060-1063