Tiny black vertical lines at the tips of the nails are clinically known as longitudinal black nails. It can extend from the nail root all the way to the nail tip. Common lesions include onychomatous nevus, onychomatous nevus, etc. The chances of malignant transformation are very small, and it usually does not need special treatment, while some of them need surgical treatment. 1. Onychomatous nevus: Onychomatous nevus is usually caused by the abnormal activation of melanocytes at the nail root, it usually does not need special treatment, and it can be avoided by avoiding infection and irritation in normal times. 2. Nail freckle-like nevus: Nail freckle-like nevus occurs in adults, usually will not be malignant and does not need special treatment. If the black vertical stripes widen rapidly in a short period of time, or ulceration or pain occurs, it suggests the possibility of malignant transformation, so it is recommended to go to the hospital for further examination, and surgical excision is needed if necessary. For patients with tiny black vertical stripes on the tips of nails, it is recommended to go to regular hospitals for timely examination and standardized treatment under the guidance of professional doctors.