Clear cell acanthoma
Introduction
Also known as "Acanthome cellules claires of Degos and Civatte", "Degos acanthoma," and "Pale cell acanthoma", clear cell acanthoma is a benign clinical and histological lesion initially described as neoplastic, which some authors now regard to as a reactive dermatosis. It usually presents as a moist solitary firm, brown-red, well-circumscribed, 5 mm to 2 cm nodule or plaque on the lower extremities of middle-aged to elderly individuals. The lesion has a crusted, scaly peripheral collarette and vascular puncta on the surface. It is characterized by slow growth, and may persist for years [1].
Dermoscopic features
'String of pearls'
Even though clear cell acanthoma has a non-specific clinical appearance, it has a relatively specific and easy to recognize dermoscopic feature called 'string of pearls', referring to dotted vessels that are arranged in a linear of serpiginous pattern [2]. The linear formations tend to coalesce into a reticular pattern, covering whole or part of the lesion [1].
The 'string of pearls' sign was found to be related to angio-eccrine hyperplasia and vascular hyperplasia of the papillary dermis, corresponding to the capillaries oriented perpendicular within the elongated dermal papillae [3].
Additional dermoscopic features [1]
- Pale pink background (90% of cases)
- Shiny white lines (60% of cases)
- Glomerular vessels (55% of cases)
- Collarette of translucent scale around the periphery of the lesion (40% of cases)
- Haemorrhagic areas (35% of cases)
- Orange crusts (15% of cases)
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Differential diagnosis
The clinical differential diagnosis includes [4]:
- Dermatofibroma
- Inflamed seborrheic keratosis
- Pyogenic granuloma
- Actinic keratosis
- Basal cell carcinoma
- Squamous cell carcinoma
- Verruca vulgaris
- Psoriasis
- Eccrine poroma
- Clear cell hidradenoma
- Melanoma.
In a recent report it was demonstrated that the 'string of pearls' sign can be seen with other epidermal lesions, as two seborrheic keratoses and one lichen planus-like keratosis presented with the classic 'string of pearls' sign. [5]
- ↑ 1.0 1.1 1.2 Lyons et al.: Dermoscopic features of clear cell acanthoma: five new cases and a review of existing published cases. Australas. J. Dermatol. 2015;56:206-11. PMID: 25495637. DOI.
- ↑ Tiodorovic-Zivkovic et al.: Dermoscopy of clear cell acanthoma. J. Am. Acad. Dermatol. 2015;72:S47-9. PMID: 25500041. DOI.
- ↑ Paolino et al.: Clinicopathological and dermoscopic features of angio-eccrine hyperplasia in clear cell acanthoma. J. Am. Acad. Dermatol. 2016;74:1259-1261.e3. PMID: 27185430. DOI.
- ↑ Tiodorovic-Zivkovic et al.: Dermoscopy of clear cell acanthoma. J. Am. Acad. Dermatol. 2015;72:S47-9. PMID: 25500041. DOI.
- ↑ Espinosa et al.: "String of pearls pattern": report of three cases of non clear-cell acanthoma. An Bras Dermatol 2017;92:142-144. PMID: 29267474. DOI.
