Keratoacanthomas multiple eruptiveD23.L

Non-familial, eruptive, multiple, solitary, also area coalescing keratoacanthomas. Multiple eruptive keratoacanthomas may occur idiopathically. More frequently, however, they occur under various immunosuppressive treatments and in underlying autoimmunologic diseases (treated with immunosuppressive therapy). An association with malignant tumors (carcinomas, lymphomas) and chronic renal failure has been reported occasionally.

Unexplained. Multiple keratoacanthomas have been described in various autoimmunological diseases (as a consequence of therapy?), such as rheumatoid arthritis and Sjögren's syndrome. Furthermore, they have been described in immunosuppressive therapies (BRAF inhibitors e.g. vemurafenib, leflunomide, imiquimod; pembrolizumab - Fradet M et al. 2019) and underlying malignancies(multiple myeloma, myelodysplastic syndrome). Eruptive keratoacanthomas occurred in a few isolated cases after tattooing (Healey B et al 2018 - see also Casuistics).

Mostly, middle age (40-60 years) or older (70-80 years). m:w=1:1

Face, neck, trunk, extremities, more rarely also mouth mucous membrane and larynx infestation Palmae and Plantae always remain free.

Multiple (sometimes hundreds), up to 1.0 cm in size, skin-coloured to reddish-brown, firm papules which, if persisting for a long time, present the characteristic clinical picture of keratoacanthoma (central horny plug with surrounding epithelial lip formation). In the early eruption phase, the typical aspect of classic keratoacanthoma is often absent. In this phase mainly reddish or skin-colored, firm, surface-smooth papules are seen.

Eruptive multiple keratoacanthomas may be markedly to excessively itchy and also differ from the classic, asymptomatic keratoacanthoma in this respect. Eruptive keratoacanthomas may also aggregate in a beet-like fashion. Involvement of the oral mucosa is possible.

During the eruption phase, there is a tendency for new keratoacanthomas to form in response to external stimuli(Köbner phenomenon), e.g. injection sites.

Etiologically unexplained is the occurrence of multiple keratoacanthomas in tattoos (Köbner phenomenon?).

Acitretin (neotigason) initial 0.5-1 mg/kg bw/day, reduction to maintenance dose, locally 10% salicylic acid. Therapy successes are poor.

Positive results with cyclophosphamide pulse therapy (1g/month i.v.) have been reported.

Furthermore, the combination of acitretin (1mg/kgkgkg per day) with methotrexate (15mg/week) was described as successful.

Prognosis quoad vitam good; quoad sanationem rather bad.

Few cases of (real) malignant degeneration, especially in the oral mucosa area, have been reported.

A 64-year-old man presented with multiple lumps that had developed over the past 6 weeks without prior treatment or examination. Sixteen months earlier, the patient had had a continuous black full-arm tattoo with a three-centimeter-thick red band around it just above the elbow. The original red portion was inked with Eternal's "Lipstick Red" ink. This tattoo healed without complication. 12 months later, the red band was tattooed again with dark red ink, also from Eternal. Three days later, the patient noticed a burning sensation within the red band; this developed into painful, draining pustules and papules that waxed and waned but continued to develop over the next 8 weeks until presentation. Clinically, there were approximately 25 firm, well-circumscribed papules and nodules, some with hyperkeratotic, crusted centers located entirely within the encircling red band. Two punch biopsies were obtained. Pathologic evaluation revealed invasive, well-differentiated squamous cell carcinoma in both specimens. Because they were pathologically squamous cell carcinomas and clinically eruptive KAs, acitretin was prescribed at a dosage of 10 mg/day. After ten weeks of therapy, the lesions had almost completely disappeared. They healed completely. No recurrence.

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