15272 Life cycle of a halo nevus: A noninvasive in vivo study using reflectance confocal microscopy

Abstract

Halo nevi consist of a central melanocytic nevus, outlined by a hypopigmented area believed to be caused by cytotoxic T-cells. They are clinically classified into stages I-IV. Stage I halo nevi contain a central pigmented nevus outlined by a circular or oval hypopigmented area; stage II halos contain a pink central nevus; stage III are described as depigmented macules lacking a central nevus; and stage IV show a partial or complete re-pigmentation of the skin. The current standard is to closely monitor or biopsy halo nevi because rarely, a similar hypopigmented pattern may arise from cutaneous melanoma. Reflectance confocal microscopy (RCM) is an innovative, noninvasive tool used to diagnose melanocytic lesions. We present a case series of ten clinically concerning halo nevi referred to our clinic. Using RCM, we determined the benign nature of the lesions and classified them according to clinical staging standards. Five were classified as Stage I, showing dermal and junctional nests, and numerous inflammatory cells lining the dermal-epidermal junction. Three were classified as stage II; confocal images showed areas of regression evidenced by dermal fibrosis, with few dermal and junctional nests. Two were classified as stage III; confocal images showed an atypical honeycomb pattern, small and large bright lymphocytes, and an absolute lack of epidermal pigmentation. None were classified as stage IV. No atypical round or dendritic melanocytes were observed in any confocal images. These findings support RCM as a viable technique for the diagnosis and monitoring of halo nevi, presenting an alternative to biopsy.