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JAMA Dermatology Clinicopathological Challenge
December 2018

A Case of Pigmented Longitudinal Melanonychia

Author Affiliations
  • 1Department of Dermatology, University of Texas Southwestern Medical Center, Dallas
JAMA Dermatol. 2018;154(12):1473-1474. doi:10.1001/jamadermatol.2018.1894

A man in his 40s presented to the dermatology clinic for evaluation of a new pigmented lesion on his left second toenail. The lesion first appeared 12 months before presentation and was progressively growing. This was his first time presenting to a physician for this problem, and no prior treatments had been attempted. The lesion was asymptomatic. He was otherwise well and denied any fevers or weight loss.

Clinical examination revealed a dark brown longitudinal pigment band covering the full length of the toenail of the left second digit with corresponding nail thickening over the pigmented band. The pigment was the same width throughout the band and extended to the proximal nail fold (Figure, A). No other nail or skin lesions were found at the time of examination. A biopsy specimen was obtained from the nail plate and nail matrix and stained with hematoxylin-eosin (Figure, B-D).

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