Why does a brown line appear on a fingernail?

Have you ever noticed a lengthwise black or brown band or streaks in your fingernails? ... could be melanoma of the nail called subungual melanoma. Nail discoloration that occurs as a vertical line is also called longitudinal melanonychia. ... C: Change has been noted in the look of the pigment band. ○ D: Digit involved. read more

Melanonychia: Longitudinal melanonychia is a brown-to-black line within the nail. It is frequently seen in patients with darker skin types and often on multiple nails. It can be seen in certain syndromes (e.g., laugier-hunziker) or due to medications. read more