Derm Dx: Pigmented Area in the Nail of the Hallux

The patient is a 42-year-old man referred by his primary care provider for evaluation of a pigmented area on his right big toe nail. He is an avid tennis player but denies antecedent trauma. Family and personal histories are negative for melanoma. Examination reveals a reddish black pigmentation of the medial nail. There is neither diffusion of pigment nor significant ...