Clear Cell Acanthoma: A Review of Clinical and Histologic Variants

Abstract

Degos and Civatte first described clear cell acanthoma (CCA) in 1962 and later in a review article found that, in most instances, the lesion was a solitary red-brown dome-shaped papule that involved the distal lower extremity. The first morphologic variant of CCA was reported as a “giant form of the acanthoma of Degos” which measured 45 × 40 mm, about twice the size of the largest CCA documented earlier. Since then, many variants of CCA have been described, including polypoid, pigmented and atypical. Herein, we describe a new variant of CCA and add another example of the polypoid variant to the literature. The new variant exhibits cellular features of trichilemmoma but architecturally differs from it. We also attempt to broaden the list of CCA variants summarized by Tempark and Shwayder by adding ours and a few more examples of CCA. The new variants of CCA include verrucous, linear, subungual and trichilemmal.

Generalized eruptive clear cell acanthomas

“…CCA was first reported by Degos in 1962 1,2 . CCA is considered a rare, benign tumorous lesion of obscure origin.…”

“…The prognosis is excellent for these lesions since they are benign. Histopathology as well as dermoscopy can be utilised to confirm the diagnosis of CCA 1,2 . On dermoscopy, highly characteristic findings can be observed assisting in the diagnosis.…”

“…Routine histopathology usually demonstrates a well‐demarcated area of the acanthotic epidermis with regular psoriasiform hyperplasia composed of pale staining keratinocytes. Moreover, an abrupt transition from the normal‐appearing nonlesional epidermis to the paler acanthotic lesional epidermis is readily apparent 1,2 …”

“…CCA was first reported by Degos in 1962. 1,2 CCA is considered a rare, benign tumorous lesion of obscure origin. Although most commonly located on the legs, CCAs may also appear on the trunk, upper extremities, face and intertrigines.…”

“…Usually, clear cell acanthoma (CCA) is a benign solitary lesion with distinctive clinicopathological features. 1,2 Disseminated eruptive CCAs have very rarely been reported. [3][4][5][6][7] We here describe a patient with generalized eruptive CCAs.…”