Non-Melanoma-Associated Dyschromia of the Proximal Nail Fold.

Subungual melanoma with pigmentation beneath the nail that extends to involve the proximal nail fold is referred to as Hutchinson's sign. Black or brown subungual discoloration involving the proximal nail fold secondary to other etiologies has been referred to as pseudo-Hutchinson's sign. Three patients with nail discoloration and concurrent dyschromia of the proximal nail fold are described: a female with a chronic subungual hematoma and pseudo-Hutchinson's sign, a male with culture-confirmed Pseudomonas aeruginosa (P. aeruginosa) of the nail with green discoloration involving the proximal nail fold, and a male with an acute subungual hematoma with red-purple subungual discoloration affecting the proximal nail fold. PubMed was searched for the following: black, brown, chloronychia, discoloration, dyschromia, green, hematoma, Hutchinson's sign, nail, nail fold, proximal, pseudo-Hutchinson's sign, red, subungual melanoma, syndrome. The papers were reviewed and appropriate references evaluated. In conclusion, melanoma-associated black proximal nail fold pigmentation is referred to as Hutchinson's sign, and non-melanoma-associated black pigmentation has been designated as pseudo-Hutchinson's sign. Subungual nail plate discoloration extending to involve the proximal nail fold may be black, green, or red-purple in patients with melanocytic and non-melanocytic lesions, bacterial infection (Pseudomonas), and acute subungual hematoma, respectively. Instead of creating a new terminology, we suggest that non-black subungual discoloration (green or red-purple) extending to involve the proximal nail fold be referred to as pseudo pseudo-Hutchinson's sign.