Like a onychomatous nevus, an onychomatous nevus is a junctional nevus in the nail matrix where the pigment spills over into the nail plate and can move forward with the growth of the nail plate, appearing as a streak of brownish-black coloring on the nail surface that persists.

The nevus of the nail is mostly benign, and very rarely can be malignant to melanoma. Most of the nails mother nevus to nail plate black line, without any symptoms. It is recommended to consult a doctor in time.