Hutchinson’s sign in congenital nail matrix nevus

Abstract

Congenital nail matrix nevi (NMN) are a rare cause of melanonychia that may present with irregularity, asymmetry, and multicomponent pigmentation posing diagnostic challenges with subungual melanoma. We report a case of a 49-year-old female with longitudinal melanonychia and a 1-month recent pigmentation in the proximal nail fold. This sign is traditionally associated with malignancy, which further complicates the differentiation from acral melanoma. Therefore, a nail matrix biopsy was performed. Histopathologic examination revealed a nail matrix nevus. This procedure is crucial in suspicious cases, despite the risk of nail dystrophia. The evolution of these nevi into adulthood and their potential malignancy remains unclear, emphasizing the need for continued research and surveillance. This case highlights that congenital NMN often present with clinical and dermoscopic features of concern, mirroring those observed in subungual melanoma.

Keywords

• Congenital melanocytic nevus. Congenital nail matrix nevus. Dermoscopy. Hutchinson’s sign. Longitudinal melanonychia. Subungual melanoma.