Keratosis palmoplantaris diffusa with mutations in KRT 9 Q82.8

Genetically heterogeneous disease group with mutation in KRT9. Epidermolytic hyperkeratosis was detectable in most of the cases followed up (Li Y et al. (2019).

In 1989 and 1994, cases of diffuse PKK were described (Norbotten type) that lacked the signs of epidermolytic hyperkeratosis (for classification of palmoplantar keratoses, see below Keratosis palmoplantaris).

Autosomal-dominantly inherited, palmoplantar cornification disorder caused by mutations in the KRT9 gene. So far, 26 mutations in this gene have been described.

Thick, waxy, yellowish, possibly cracked, plate-like horny layer, which covers the entire palm of the hand and also the sole of the foot. It is sharply separated from the normal skin by a pinkish red seam. The mobility of the hands is often limited, fingernails usually grow abnormally like a watch glass, and the sense of touch and temperature can be disturbed.

Occasionally there are brownish ankle pad-like hyperkeratoses (knuckle pads)

After strong mechanical stress, especially in combination with heat, exacerbations with painful rhagade formation are possible.

Hyperhidrosis often exists. The keratoses macerate and decompose, accompanied by a foetus that smells bad.

There is a danger of mycotic or bacterial superinfections.

Massive thickening of the horny layer focally with epidermolytic hyperkeratosis.

Symptomatic: In case of mycotic or bacterial overlay, appropriate local therapy with local disinfectants or antimycotics. Intensive and consequent care of the hyperkeratotic areas with salicylic acid containing R227 or urea containing ointments R106; if necessary under hourly occlusion.

Supplementary: Mechanical removal with a corneal plane or pumice stone after a 10-15 minute soft soap bath.

1. Devos SA, Delescluse J (2003) An unusual case of palmoplantar keratoderma. J Eur Acad Dermatol Venereol 17: 68-69
2. Gamborg N et al (1994) The dominant form of hereditary palmoplantar keratoderma in the northernmost county of Sweden (Norbotten). Dermatology 188: 188-193
3. Li Y et al. (2019) Genetic Analysis of KRT9 Gene Revealed Previously Known Mutations and Genotype-Phenotype Correlations in Epidermolytic Palmoplantar Keratoderma. Front Genet 9:645.
4. Lu Y et al (2003) A novel mutation of keratin 9 in epidermolytic palmoplantar keratoderma combined with knuckle pads. Am J Med Genet 120: 345-349
5. Loh Teck-Hiong et al (2003) Palmar-plantar keratoderma of Unna Thost associated with atopic dermatitis: An underrecognized entity? Pediatric Dermatol 20: 195-198
6. Steijlen FM et al (1999) Palmoplantar keratodermas. In: Traupe H, Hamm H (eds) Pediatric Dermatology, Springer Verlag Berlin Heidelberg New York 71-72.
7. Thost A (1880) On hereditary ichthyosis palmaris et plantaris corneae. Inaugural dissertation. Heidelberg
8. Unna PG (1883) On keratoderma palmare et plantare hereditarium. A study in kerato-nosology. Arch Dermatol Syph (Berlin) 15: 231-270.
9. Vorner H (1901) Zur Kenntniss des Keratoma hereditarium palmare et plantare. Arch Derm Syph 56: 3-31