Keratosis follicularis spinulosa decalvans Q82.84

Rare, x-linked dominant heterogeneous genodermatosis characterized by atrophic follicular keratinization abnormalities in typical localization of the common keratosis pilaris (capillitium, face, eyebrows, extensor sides of extremities, thorax, gluteae), scarring alopecia of the scalp, and palmo-plantar keratoses. The disease occurs in full expressivity only in the male sex.

Further inconstantly associated are changes of the nails(leukonychia) as well as other symptoms.

Probable X-linked dominant inheritance. Localization of a gene defect on the X chromosome, Xp 22.2-p22.13. Mutations in the MBTPS2 gene (Xp22-12-Xp22.11) are detectable.

The MBTPS2 gene (membrane-bound transcription factor protease,site2) is a membrane-bound zinc metalloprotease that controls proteins (SREbPs = sterol regulatory element-binding proteins) that control cholesterol metabolism. Apparently, there are associations with Olmsted syndrome, as both phenotypes were present in a Chinese family. The full-blown disease is found only in the male sex.

The clinical picture of this generalized follicular keratinization anomaly depends on the localization involved. Keratosis follicularis spinulosa decalvans may affect the body parts covered with vellus hairs (the usual marrowless body hair - picture of stretching, rubbing keratosis pilaris), the area of bristle hairs or also certain areas of long hairs(scarring alopecia). The morphological diversity of the clinical picture often makes its definite classification difficult.

Other associated symptoms include:

• palmo-plantar keratoses
• leukonychia
• keratitis with corneal opacities
• photophobia
• persistent ductus botalli and
• hypospadias.

Keratosis follicularis akneiformis, type Siemens; ulerythema ophryogenes, erythromelanosis follicularis faciei et colli, Lichen spinulosus

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