Supplementary Material for: Dermatofibroma with hypopigmented Meyerson halo: case report and review of non-melanocytic hosts

Meyerson phenomenon denotes a perilesional, classically eczematous halo around a pre-existing lesion, most often melanocytic. Non-melanocytic halos are uncommon and can mimic regression in a melanocytic lesion, including melanoma, leading to urgent referrals. We report a 37-year-old woman with a "mole with a halo" on her arm. Examination revealed a 5-mm pink papule with a thin whitish collarette and a faint, ill-defined hypopigmented ring. Dermoscopy showed a structureless pink center with a pinpoint crust and delicate collarette, but no pigment network or organized vascular pattern. Excisional biopsy revealed a dermal spindle-cell proliferation characteristic of dermatofibroma; the diagnosis was confirmed by negative SOX10 and positive Factor XIIIa staining. Notably, there was no spongiotic perilesional dermatitis. A targeted literature review confirmed the rarity of halos around dermatofibromas, which are typically eczematous. Our case expands the clinicopathologic spectrum to include a hypopigmented, non-eczematous Meyerson-like (“forme-fruste”) halo variant and supports a dermoscopy-first approach to avoid over-triage to melanoma and help streamline care.