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.
Lam C, Weyant GW, Billingsley EM. Longitudinal Melanonychia of the Toenail. JAMA Dermatol. 2014;150(4):449-450. doi:10.1001/jamadermatol.2013.8358