Keratosis palmoplantaris cum degeneratione granulosa Q82.8

Autosomal-dominantly inherited planar palmoplantar keratosis. Most likely, epidermolytic palmoplantar keratosis type Vörner (EPPK) and palmoplantar keratosis type Unna-Thost represent either clinically and genetically distinguishable variants of the same disease or they are one and the same disease(PPK type Unna-Thost-Vörner) whose clinical expression shows a certain variation due to the 26 possible underlying mutations in the KRT9 gene (17q12-q21).

In this respect, the historical nomenclature possibly only insufficiently differentiates and defines this spectrum of manifestations with regard to the phenotypic-genotypic correlation.

In contrast, keratosis palmoplantaris diffusa circumscripta type Norrbotten(synonyms: Non-epidermolytic palmoplantar keratoderma; autosomal dominant diffuse palmoplantar keratoderma, Norrbotten type;diffuse palmoplantar keratoderma, Bothnian type) as a diffuse palmoplantar keratosis with non-epidermolytic hyperkeratoses and with underlying mutation in the aquaporin-5 gene (AQP5, 12q13.12) occupies a genetically and phenotypically clearly defined special position.

Defective structure of keratin due to point mutations in the gene for keratin 9 (KRT9), which is mapped on chromosome 17q12-q21. Mutations in the KRT1 gene are rarer.

Keratin 9 is expressed in the suprabasal layers of the epidermis and is specific for the skin on the palms of the hands and soles of the feet. Mutations in the keratin 9 gene lead to the breakdown of the keratin filament network and cytolysis of corneocytes.

Diffuse, non-transgenic cornification with sharp edges, red rim and ankle-cushion-like hyperkeratosis on the extensor sides of hands and feet, also watch-glass nails. Occasionally hyperhidrosis palmaris or plantaris.

1. Devos SA et al (2003) An unusual case of palmoplantar keratoderma. J Eur Acad Dermatol Venereol 17: 68-69
2. Küster W et al (1995) Keratosis palmoplantaris diffusa Vörner. Dermatologist 46: 705-10
3. Loh TH et al (2003) Palmar-plantar keratoderma of Unna Thost associated with atopic dermatitis: an underrecognized entity? Pediatric dermatol 20: 195-198
4. Lucker GPH et al (1994) Topical calcipotriol in the treatment of epidermolytic palmoplantar keratoma of Vörner. Br J Dermatol 130: 543-5
5. Maruyama R (1999) A case of Unna-Thost disease accompanied by Epidermophyton floccosum infection. J Dermatol 26: 63-66
6. Mofid MZ et al (1998) Hereditary epidermolytic palmoplantar keratoderma (Vorner type) in a family with Ehlers-Danlos syndrome. J Am Acad Dermatol 38(5 Pt 2): 825-830
7. Reis A et al (1994) Keratin 9 gene mutations in epidermolytic palmoplantar keratoderma (EPPK). Nat Genet 6: 174-179
8. Thost A (1880) About hereditary ichtyosis palmaris et plantaris cornea. Dissertation (Heidelberg)
9. Unna PG (1883) About the Keratoma palmare et planttare hereditarium. Quarterly Derm Syph (Vienna) 15: 231
10. Vorner H (1901) For the knowledge of Keratoma hereditarium palmare et plantar. Arch Derm Syph 56: 3-31
11. Yang JM (1998) Mutations in the 1A rod domain segment of the keratin 9 gene in epidermolytic palmoplantar keratoderma. Acta Derm Venereol 78: 412-416