A greenish-black discoloration of the nail plate caused by a Pseudomonas bacterial infection, often in a nail lifted by onycholysis.
A brown or black longitudinal band in the nail plate, which can be benign (nevus) but requires evaluation to rule out melanoma.
A longitudinal melanonychia that is concerning for melanoma, often suggested by a wide (>3mm), variegated, or spreading band with pigment on the nail fold (Hutchinson's sign).
A rare syndrome where the nails become thick, slow-growing, and yellow-green, and are associated with lymphedema and chronic respiratory problems.
