Hyperkeratosis lenticularis perstansL85.8

Rare, probably autosomal dominant inherited androtropic genodermatosis with disseminated small papular keratoses on the lower legs persisting chronically over years. The term "lenticularis" refers to the lenticular-sized (or even larger), flat whitish plaques.

Unknown, most likely autosomal dominant inheritance; also sporadic; probably a disorder of keratinocyte proliferation plays a role. Associations with primary hyperaldosteronism have been described (Zhang X et al. 2018).

In the second half of life, m>w.

Beginning on the back of the foot in middle age, later spreading to the extensor sides of the lower legs and possibly including the thighs, arms, back of the hands and rarely the trunk (here also described as a unilateral cutaneous mosaic). After detachment of the firmly adhering horny scales, punctiform bleeding appears at the base. Also soles of the feet and palms may be involved; here appearing as small horny papules (pits).

Disseminated, symmetrical, asymptomatic, up to 0.5 cm large, centrally sunken, brown-red or even whitish, hyperkeratotic papules with firmly adherent scaling. Dewdrop-like bleeding after removal of the scale. Confluence results in small psoriasiform foci. Unilateral distribution patterns have also been described (Urbina F et al. 2016).

Bowl-shaped depressed surface relief. Here, compact orthohyperkeratosis, sometimes also parahyperkeratosis with uniform epidermal atrophy. Lesional, band-like (but not epitheliotropic), lymphocytic infiltrate in the upper dermis; absence of elastic fibers. Laterally, the epithelium is acanthotic and encompasses the central horny papule in a collerette-like fashion.

Electron microscopy: absence of Odland bodies in the keratinocytes.

Clinical:

• Porokeratosis superficialis disseminata actinica. disseminated, UV-exposed areas, anular suture pattern.
• Psoriasis vulgaris: rarely only on the lower legs. Psoriasis phenomenon can be triggered.
• Hyperkeratosis follicularis et parafollicularis in cutem penetrans: the consistency of M. Felgel is doubted, because transitions to M. Kyrle have been described.
• Lichen planus: color of lichen planus is reddish-livid, usually itching; rarely localized only on the lower legs
• Stuckokeratosis: whitish-powdery, scratchable keratoses.
• Verrucae vulgares: more common in young people, localization uncommon; histology may be diagnostic.

Histologic:

• Stukkokeratosis: marked acanthosis and papillocatosis with sawtooth-like relief.
• Porokeratosis superficialis disseminata actinica: always evidence of a flag-like parakeratosis cone here.
• Lichen planus: Interface dermatitis which is completely absent in lichen disease.

Treatment trial with 5% 5-fluorouracil cream(Efudix) under occlusion 2 times/day for several weeks under stationary conditions.

Alternatively: glucocorticoid externa.

In addition to this, nurturing (urea-containing) external agents such as Ungt. emulsif. aq. and 5% urea cream R102.

Acitretin in low dosage (5-10 mg/day) leads to success in some cases.

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8. Ravat FE et al (2003) Case 3: widespread scaly papules affecting a patient's limbs and pinnae giving the skin a rough feeling. Diagnosis: Flegel's disease. Syn. hyperkeratosis lenticularis perstans. Clin Exp Dermatol 28: 339-340.
9. Wilson PD et al (1980) Treatment of hyperkeratosis lenticularis perstans (Flegel) with topical fluorouracil. Dermatologica 160: 337-340
10. Urbina F et al (2016) A case of localized, unilateral hyperkeratosis lenticularis perstans on a woman's breast. J Dtsch Dermatol Ges 14:416-41.
11. Zhang X et al (2018) Hyperkeratosis lenticularis perstans in a patient with primary hyperaldosteronism. J Dtsch Dermatol Ges 16: 72-73.
12. Zimmermann R (2001) 40 years to Flegel's disease (hyperkeratosis lenticularis perstans). Dermatol 52: 231-235