A 46-year-old woman requests removal of a growth on her abdomen. The lesion, which has been present for at least 1 year, has increased in size and has recently been traumatized. The patient is obese and currently taking medications to control hypertension and hyperlipidemia. Physical examination reveals a 2.0cm firm nodule with a reddened center. Palpation of the area did not elicit tenderness and no similar lesions were noted.
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Clear cell acanthoma (CCA) was first described in 1962 by Degos et al; it is also known as Degos acanthoma and acanthoma cellules Claire of Degos and Civatte.1 The origin of CCA is uncertain and the condition may represent either a benign neoplastic process or a reactive inflammatory dermatosis.2
Clinically CCA presents as a solitary, slow-growing, well-circumscribed, red-pinkish nodule with a diameter ranging from 5mm to 2cm.3 A peripheral, wafer-like scale collarette is found in a majority of cases.4 Many variants of CCA have been described including giant, polypoid, pigmented, eruptive, cystic, and atypical.5
The lesion occurs most commonly in middle-aged to older adults with no gender predilection.5 The most common site of involvement is the lower limbs; although cases have been reported on the trunk, face, inguinal area, scalp, and vermilion mucosa of the lips.6
Diseases that mimic CCA include pyogenic granuloma, benign lichenoid keratosis, inflamed seborrheic keratosis, eccrine poroma, and malignancies including basal cell carcinoma and amelanotic melanoma. Dermoscopy can aid in distinguishing CCA from other nonpigmented lesions. The presence of glomerular or pinpoint blood vessels in a curvilinear and reticular pattern resembling a pearl necklace is a characteristic pattern.7 On histology, CCA presents with psoriasiform epidermal hyperplasia sharply demarcated from the normal adjacent epidermis.8 The glycogen content of the clear cells stains positive for periodic acid-Schiff stain.9
Treatment by excision is curative. Cryotherapy and carbon dioxide laser therapy have been used to treat multiple lesions.10,11
Alexandra Stroia, BS, is a medical student at the Lake Erie College of Osteopathic Medicine. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
1. Degos R, Delort J, Civatte J, Poiares Baptista A. [Epidermal tumor with an unusual appearance: clear cell acanthoma.] Ann Dermatol Syphiligr (Paris). 1962;89:361-371.
2. Benedetto CJ, Athalye L. Clear cell acanthoma. In: StatPearls. StatPearls Publishing; July 13, 2021.
3. Pogorzelska-Antkowiak A, Bergler-Czop B, Antkowiak. The complexity of clear cell acanthoma diagnosis based on the literature review. Postepy Dermatol Alergol. 2020;37(3):443-444. doi:10.5114/ada.2020.96270
4. Usmani A, Qasim S. Clear cell acanthoma: a review of clinical and histologic variants. Dermatopathology (Basel). 2020;7(2):26-37. doi:10.3390/dermatopathology7020005
5. Tempark T, Shwayder T. Clear cell acanthoma. Clin Exp Dermatol. 2012;37(8):831-837. doi:10.1111/j.1365-2230.2012.04428.x
6. Monari P, Farisoglio C, Gualdi G, Botali G, Ungari M, Calzavara-Pinton P. Multiple eruptive clear cell acanthoma. J Dermatol Case Rep. 2010;4(2):25-27. doi:10.3315/jdcr.2010.1048
7. Cunha DG, Kassuga-Roisman LEBP, Silveira LKCB, Macedo FC. Dermoscopic features of clear cell acanthoma. An Bras Dermatol. 2018;93(3):449-450. doi:10.1590/abd1806-4841.20186977
8. Veiga RRG, Barros RS, Santos JEB, Castro Abreu Junior JM, Bittencourt MJS, Miranda MFR. Clear cell acanthoma of the areola and nipple: clinical, histopathological, and immunohistochemical features of two Brazilian cases. An Bras Dermatol. 2013;88(1):84-89. doi:10.1590/s0365-05962013000100010
9. Wah Y, Usatine RP, Fernandez MP. A shiny red papule in an older person. Clear cell acanthoma. Am Fam Physician. 2013;88(4):261-262.
10. Hatakeyama M, Oka M, Fukunaga A, Kunisada M, Funasaka Y, Nishigori C. A case of multiple facial clear cell acanthomas successfully treated by cryotherapy. Indian J Dermatol. 2013;58(2):162. doi:10.4103/0019-5154.108122
11. Chi CC, Wang SH, Huang HS. Clear cell acanthoma successfully treated with a carbon dioxide laser. Dermatol Surg. 2005;31(10):1355-1358. doi:10.1111/j.1524-4725.2005.31220