MD Podiatrist Discusses Subungual Dark Spots

According to Dan Michaels, DPM, dark vertical bands on the toenail or dark spots under the nail could be a sign of pigment deposits, trauma, or skin cancer.
If a dark brown or black discolored straight vertical stripe appears on the nail, this could indicate melanonychia – which can be caused by injury or illness. “The darker your skin tone, the higher chance you have of developing dark stripes in your nails. These will usually be seen in the 5th and 1st nails but can appear in all,” he said. Dark stripes could also be a sign of melanoma – a type of skin cancer that develops from skin cells called melanocytes – Dr. Michaels warned.