Symptoms
The so-called melanonychia longitudinalis manifests itself in a uniform brown to black stripe that runs along the entire nail plate. It is thin or up to a few millimeters wide. The nail change is often observed in dark-skinned people.
Causes
The cause lies in the production of the pigment melanin, which is formed by activated melanocytes in the matrix of the nail. Triggers include, for example, a mole or, less commonly, a malignant melanoma. The melanocytes can be activated by physiological conditions (e.g., pregnancy), but also pathophysiologically (diseases) or iatrogenically (e.g., drugs).
Diagnosis
Because melanonychia may be due to malignant cancer or other disease, patients should always seek medical treatment as a precaution.
Treatment
If desired, the pigment focus in the nail matrix can be removed by minor surgery. Melanoma must always be treated see also under melanoma. Treatment is based on the cause.
