Melanoma mimic in epidermolysis bullosa simplex

Published Date: 19th July 2016

Publication Authors: Sharma N, Ellison J, Walsh ML

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Abstract

Epidermolysis bullosa (EB) simplex (EBS) is a mechanobullous disease characterized by blistering, typically of the hands and feet, following friction or minor trauma. A less well-recognized phenomenon in this condition is the sudden development of atypical naevi. We report the case of a 27-year-old hairdresser with a clinical diagnosis of EBS who presented with an abnormal pigmented area on the dorsum of the right foot. This developed after an episode of severe blistering at this site. The pigmented area was noted to have a suspicious appearance at a routine appointment. There was no family history of melanoma. On examination she had classical EBS bullae on both soles. Of greater concern, at the time, was a significant 4 x 6-cm verrucous pigmented lesion involving the fourth and fifth toes, fulfilling the ABCD criteria for melanoma. Dermatoscopically this had an irregular pigmented network and hyperpigmented streaks. At this stage the features were suspicious for a superficial spreading melanoma. However, a large incisional biopsy showed that this was histologically a benign compound naevus, confirmed upon review by our dermatopathologist. Eruptive naevi of EB are a relatively newly reported entity. These naevi appear at sites of former repetitive blistering and are large, asymmetrical lesions with irregular pigmentation, which can mimic melanoma both clinically and dermatoscopically. However, they have a more benign histological appearance resembling either a compound naevus in EBS or more problematically a pseudomelanoma in recessive dystrophic EB (Cash SH, Dever TT, Hyde P, Lee JB. Epidermolysis bullosa nevus: an exception to the clinical and dermoscopic criteria for melanoma. Arch Dermatol 2007; 143: 1164-7). The lesions are more commonly noted to arise in childhood or adolescence, becoming more papular or verrucous with age, and can range from 3 to 15 cm in size. They may be more common than the literature leads us to believe, with Bauer et al. describing 14% of patients on the Austrian EBS register with similar features. None of these cases was found to undergo malignant transformation over a period of 20 years of surveillance (Bauer JW, Schaeppi H, Kaserer C et al. Large melanocytic nevi in hereditary epidermolysis bullosa. J Am Acad Dermatol 2001; 44: 577-84). There is a need to raise awareness of this subcategory of naevus to avoid misdiagnosis, anxiety and unnecessary therapeutic intervention.

Llewellyn, R; Walsh, M; Sharma, N; Ellison, J. (2015).  Melanoma mimic in epidermolysis bullosa simplex . British Journal of Dermatology. 173 (Suppl 1), 15-16.

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