Clear cell acanthoma

Abstract

SummaryClear cell acanthoma (CCA), is an asymptomatic benign lesion of unknown origin and aetiology, which typically presents as a red to brown, dome-shaped papule on the leg. We discuss the case of a patient with an irregular plaque of hypopigmented papules whose diagnosis of CCA was only made by biopsy, and review the characteristic presentation, uncommon variants, locations and associated conditions of this lesion. The diagnosis is based on histopathology and ⁄ or immunohistochemistry, but the variable clinical presentation may make diagnosis difficult. The differential diagnosis includes skin tumours and inflammatory and pigmentary dermatoses. The lesions do not regress spontaneously, and excisional removal is the preferred treatment.

Topical calcipotriol as a new therapeutic option for the treatment of clear cell acanthoma

“…2 Given the frequent comorbidity with systemic diseases and the psychological aversion to surgery, a conservative approach answers better to the needs of older patients and should be considered due to the lower risk of side effects. Calcipotriol is officially indicated for the treatment of psoriasis because of its ability to inhibit keratinocytes proliferation and promote their differentiation.…”

“…1 It usually presents as a single dome-shaped, sharply circumscribed, red-brown papule, often localized on the lower extremities of elderly people, although unusual presentations have been reported. 2,3 Dermoscopy enables a very confident diagnosis in many cases, due to the presence of a very characteristic pattern constituted by widespread pinpoint-like, dotted and/or glomerular vessels, linearly arranged as a string of pearls to create a network-like appearance. 4 …”

“…However, surgical excision is usually performed, as many cases are misdiagnosed as basal cell or squamous cell carcinomas. 2 …”

Clear cell acanthoma on the dorsum of the hand

“…[2][3][4][5] Numerous pink/red coloured dots, arranged in a string-like or reticular fashion, representing vascular structures, are the dermatoscopic hallmark of CCA. 1 CCA is currently defined as solitary well-demarcated, red/brown papule that usually appears with a collarette of scale and central crusting.…”

“…1 CCA is currently defined as solitary well-demarcated, red/brown papule that usually appears with a collarette of scale and central crusting. [2][3][4][5] CCA lesions develop slowly during multiple years, appearing almost standard on the leg of middle-aged to elderly individuals without association with gender or race. 6 Histopathological hallmarks are epidermal acanthosis and areas of keratinocytes that have clear cytoplasm and are positive for the PAS reaction due to glycogen content.…”