white spot in the beard

A 72-year-old hardware store employee came in for a usual physical examination. His vital signs were normal, and he had no fevers, chills, night sweats, or unintended weight loss. His sole concern was a non-tender lesion on his fingernail that he had discovered three months before. He had not had any recent trauma. A longitudinal melanonychia on the radial edge of the left thumbnail was discovered during physical examination. Over the proximal nail fold, there was brown-black pigmentation. A V-shaped nick in the nail plate was evident at the distal end of the streak, and the pigment tapered distally. Based on the patient's history and current symptoms,