A man in his 60s presented with a pigmented nail streak on the left fourth toenail that had been present for 10 months. He denied pain, tenderness, or trauma. Physical examination revealed a 4-mm wide pigmented streak with varying shades of brown and longitudinal ridging (Figure, A). The nail fold was uninvolved. Because of suspicion for melanoma, a biopsy was recommended. A nail avulsion was performed and demonstrated a 3-mm tan papule beneath the proximal nail fold (Figure, B). The histologic findings are shown in Figure, C.