Multiple reddish weeping nodules on the genital area of a girl. Giant clear cell acanthoma (CCA)

Clear cell acanthoma

Clear cell acanthoma is a rarely diagnosed tumor with variable clinical morphology that is usually only recognized by its histopathological features. The primary lesion is a red papule a few millimeters in diameter that often occurs as a single lesion on the lower extremities. In dermoscopy, resemblance of the vessels to a string of pearls is a largely specific finding of clear cell acanthoma. In contrast to the initially uncharacteristic clinical findings, histopathology of clear cell acanthomas is characterized by a typical compact, well-demarcated acanthosis consisting of pale-staining, PAS-reactive keratinocytes. As etiology and pathogenesis are both unclear, nosology of clear cell acanthoma is also controversial, with an ongoing debate as to its classification as cutaneous neoplasia or reactive inflammatory dermatosis.

Clear Cell Acanthoma: A Review of Clinical and Histologic Variants

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.

Pale (Clear) Cell Acanthoma of the Palate

Clear cell acanthoma (CCA), also known as pale cell acanthoma, represents a rare benign epidermal tumor with strong predilection for the lower extremities of middle-aged individuals and no frank gender preference. The etiology of CCA is poorly understood, although a localized psoriasiform reaction is favored. Herein, we report on the clinicopathologic and immunohistochemical features, and HPV status of an apparent example of oral CCA. A 58-year-old female presented with a well-circumscribed, asymptomatic, exophytic, sessile and erythematous nodule of the right hard palate, measuring 0.7 cm in greatest dimension. Microscopically, the lesion featured parakeratosis and acanthosis with neutrophilic microabscesses and broad elongated rete pegs. In areas, spinous epithelial cells exhibited pale or clear cytoplasm without nuclear pleomorphism, mitoses or cytologic atypia. The supporting connective tissue revealed mild chronic inflammation with few scattered neutrophils and numerous capillary vessels. PAS histochemical stain with and without diastase disclosed the presence of cytoplasmic glycogen in the pale cells. The majority of glycogen-rich epithelial cells stained strongly for EMA and were negative for D2-40. Ki-67 immunostaining was confined only to the basal cell layer of the epithelium. A diagnosis of CCA was rendered. The lesion was negative for human papillomavirus (HPV) infection, as assessed by HPV-DNA PCR using the MY09/11 primers for the L1 conserved region, thus HPV infection does not appear to contribute to the pathogenesis of oral CCA. In conclusion, we report an intraoral example of CCA in order to raise awareness about this entity.

Multiple clear-cell acanthomas

Clear-cell acanthoma (CCA) usually presents as a solitary lesion involving the lower extremities. The abrupt onset of multiple CCA has been rarely reported. Such presentation may impose clinical diagnostic and therapeutic challenges. A 52-year-old man with multiple CCA is presented in this communication. The value of dermoscopy has been demonstrated in the setting of CCA. However, because of the unusual clinical presentation reflecting confocal microscopy was also performed in this case to enhance the accuracy of the clinical and dermoscopic diagnosis.

Clear cell acanthoma

Clear 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.