Halo phenomenon with regression of acquired melanocytic nevi: a case report.

We report a case of halo-phenomenon in excisional biopsy of junctional nevi in a 19-year-old girl. The diagnosis was established histopathologically because of the lack of clinical halo and unspecific dermoscopic features. Clinicopathologic difficulties in establishing the diagnosis of these pigmented lesions, etiopathogenesis and differential diagnosis of halo nevi are emphasized. Dermatologists should be familiar with the possible changes in benign melanocytic nevi, halo reactions and possible complete regression of melanocytic nevi. Diagnostic difficulties are seen in the ultimate phase of regression when melanocytes are diminished or destroyed with immune reaction.