Clear Cell Acanthoma: A Clinical, Dermatoscopic, and Histological Review. John Howard, DO*, Andrei Gherghina, DO, MS*, Jacquiline Habashy, DO*, Stanley Skopit, DO, FAOCD, FAAD** *Dermatology Resident, Larkin Community Hospital Department of Dermatology ** Program Director, Larkin Community Hospital Department of Dermatology Abstract Clinical Findings Histopathology Clear cell acanthoma (CCA) is an uncommon benign epidermal tumor, presenting CCAs are generally solitary, asymptomatic, red or brown dome shaped papules or nodules. They may be covered Typically, CCAs are characterized by well demarcated epidermal hyperplasia as an erythematous solitary papule with a peripheral scale, usually on the lower by scaled edges or a have a moist appearance. The size of the lesion can range from approximately 3-20mm made up of large keratinocytes and basal cells full of a glycogen-rich cytoplasm extremity. Although biopsy is commonly performed for diagnosis, perceptive and can slowly grow for up to 10 years. When closely examining the surface of the lesion, vascular puncta are positive to periodic-acid-Schiff staining. An abundance of densely packed dilated clinicians may suspect a CCA with the use of clinical and dermatoscopic findings. present, which easily bleed following minor trauma. These lesions are usually found on the lower extremities capillaries are seen in a well-demarcated distribution, which correlate with the We present our case of a suspected clear cell acanthoma confirmed by biopsy in middle aged to elderly adults, males and females alike [5-6]. dermatoscopic vascular features or red dots and globules outlined above. along with a clinical, dermatoscopic and histological review. Although this description is the most common presentation, there are a variety of clear cell acanthoma types Parakeratosis, neutrophilic exocytosis and mild spongiosis are also present creating a large list of differential diagnosis. These types include; giant, polypoid, pigmented, eruptive, (Images 3 and 4) [3,6]. atypical and cystic [6]. Case Report Management and Therapy A 68-year-old white female presents to our outpatient clinic for a full body skin CLINICAL, DERMATOSCOPIC, AND HISTOLOGIC PRESENTATION OF CCA exam. Her past medical history is significant only for chronic obstructive Management of CCA is excisional removal of a solitary lesion. This can be done pulmonary disease. She denies personal or family history of skin cancer. Physical through a variety of methods including, but not limited to, standard surgical exam subsequently reveals a sharply demarcated 0.3x0.3-cm shiny, pink, moist, excision, Mohs micrographic surgery, cryotherapy, electrofulguration, curettage or blanchable papule with a collarette scale located on the left anterior distal shin in carbon dioxide laser. For cases of multiple or larger size lesions, cryotherapy and conjunction with varicose veins (Image 1). Dermatoscopic evaluation showed carbon dioxide laser have been successfully used [6]. In addition, with the dotted vessels arranged in a linear “string of pearls” distribution, revealing the theorized inflammatory reactive cause, a case report showed the regression of characteristic dermatoscopic dermoscopicttern seen in clear cell acanthoma (CCA) CCA after a two month trial of calcipotriol [4]. In the case of our patient, shave (Image 2) [1,2]. excision combined with electrofulguration was used for diagnosis and treatment. Discussion Conclusion CCA is a diagnosis that can be suspected clinically, but does have a large differential diagnosis base. Due to this and the fact that it occurs rarely, CCAs have a large differential including many lesions that are less benign and misdiagnosis is not unusual. Dermatoscopically, however, this lesion has very which occur with much higher frequencies in the population. Under these unique and specific features, which greatly improves diagnostic accuracy. The conditions, the diagnosis of a CCA is usually one that is made histologically, after dermatoscopic features show a stereotypical vascular pattern composed of dotted a biopsy has been performed. Since the features of this lesion are vessels distributed linearly like a string of pearls. dermatoscopically distinct, this may afford the clinician more diagnostic confidence. The use of routine dermatoscope may therefore lessen biopsies of this History benign dermatologic entity. CCA is also known as, Degos acanthoma or Acanthome cellules claires of Degos Differential Diagnosis BIBLIOGRAPHY and Civatte [3]. There are currently no known risk factors, and the etiology is unknown. Yet, it is theorized that CCA may be due to an inflammatory reaction secondary to an unknown trigger [4]. Further investigation is necessary to CCA has a vast differential diagnosis which includes actinic keratosis, lichenoid keratosis, pyogenic granuloma, dermatofibroma, basal cell carcinoma, 1. Zalaudek I, Kreusch J, Giacomel J, Ferrara G, Catricalà C, Argenziano G. How to diagnose nonpigmented skin tumors: a review of vascular structures seen with dermoscopy: part II. Nonmelanocytic skin tumors. J Am Acad conclude the actual cause. squamous cell carcinoma, inflamed seborrheic keratosis, eccrine poroma, clear cell hidradenoma, amelanotic melanoma, and psoriasis [7]. When considering non-pigmented skin lesions such as these, dermatoscopic dermoscopicructures are often helpful in making a correct diagnosis [1]. Among this wide Dermatol. 2010 Sep;63(3):377-86; quiz 387-8. differential base, clear cell acanthomas are unique in their dermatoscopic distribution of dotted or globular vessels, arranged in a curvilinear pattern. 2. Miyake T, Minagawa A, Koga H, Fukuzawa M, Okuyama R. Histopathological correlation to the dermoscopic feature of "string of pearls" in clear cell acanthoma. Eur J Dermatol. 2014 Jul-Aug;24(4):498-9. Synopsis 3. William J, Berger T, Elston D, Odom R, Andrews G. Andrews’ Diseases of the Skin: Clinical Dermatology. Philadelphia: Saunders Elsevier, 2006. 4. Gaetano S, Giovanni P. Topical Calcipotriol as a New Therapeutic Option for the Treatment of Clear Cell Diagnosis Acanthoma. An Bras Dermatol. Anais Brasilerios De Dermatologia 89.5 (2014): 803-05. CCA is a benign lesion that is oftentimes difficult to diagnose with clinical 5. Tempark T, Shwayder T. Clear Cell Acanthoma. Clinical and Experimental Dermatology 37.8 (2012): 831-37. observation alone. CCA shares clinical features which overlap with a variety of 6. Fine RM, Chernosky ME. Clinical Recognition of Clear Cell Acanthoma. Arch Dermatol 1969; 100: 559-63. other lesions, making the differential diagnosis extremely broad. CCA, however, CCA may be suspected on physical exam, especially when combined with the clues and patterns visualized with a dermatoscope. Confirmatory diagnosis of 7. M. Ardigo, R. Buffon, A. Scope, C. Cota, P. Buccini, E. Berardesca, et al. Comparing in vivo reflectance confocal has unique dermatoscopic characteristics which make it distinct from other clear cell acanthoma requires a skin biopsy. With this in mind, dermatoscopically, these lesions are set apart from their differentials by the pattern of their microscopy, dermoscopy, and histology of clear-cell acanthoma. Dermatol Surg, 35 (2009), pp. 952-959. entities. The use of dermoscopy can thus strengthen the diagnostic suspicion of vasculature, rendering a skin biopsy practically unnecessary. Under a dermatoscope, clear cell acanthomas portray pinpoint vessels in a linear pattern, 8. Husein E, Cachaza J, Fernandez J. Dermoscopy of Clear Cell Acanthoma. J Am Acad Dermatol. 64.2 (2011) described as pearls on a string [8]. AB77. CCA..