A Congenital Melanocytic Nevus With Halo Phenomenon and Complete Regression Following Surgical Excision.

We present a case of a 4-year-old girl who underwent two planned staged surgical resections of a benign-appearing medium-sized congenital melanocytic nevus (CMN) on the right buttock. The nevus was 4 cm in diameter, medium brown in color, and exhibited central hypertrichosis with mild cobblestoning. Ten days after the first excision, a striking depigmented halo was noted around the residual nevus, which over time progressed to complete clinical regression of the residual CMN. While spontaneous development of the halo phenomenon in CMNs has been previously reported, no cases of this immune response occurring immediately after surgical excision have been documented in the pediatric population.

Abstract from PubMed