Background: Large acquired melanocytic nevi that occur in patients with epidermolysis bullosa (EB), referred to as EB nevi, may pose a diagnostic challenge because of their clinical and dermoscopic resemblance to melanoma. These unconventional melanocytic nevi have been encountered in all categories of hereditary EB, most of them in childhood. Although some of the reported cases have an alarming clinical appearance that is indistinguishable from melanoma, long-term follow-up has confirmed the benign nature of these rarely encountered melanocytic lesions. The histopathologic patterns of these nevi range from a banal congenital pattern to the problematic persistent pseudomelanoma pattern.
Observation: We describe the clinical, dermoscopic, and histopathologic features of a large EB nevus in a toddler. Clinically, the lesion was markedly asymmetrical and irregularly pigmented with foci of stippled pigmentation and scarring, which easily fulfilled the ABCD criteria for melanoma. Accordingly, a false-positive score resulted when dermoscopy was performed. Histopathologically, a pattern of persistent melanocytic neoplasm was observed. In the following 18 months, dynamic changes of the lesion included near-complete disappearance of the pigment, which was replaced by scar, milia, and areas of healing ulcers.
Conclusion: Epidermolysis bullosa nevi are dynamic melanocytic lesions that may simulate melanoma.