Melanonychia refers to a condition characterised by a discoloured nail. Typically, melanonychia appears as a blackish-brown discolouration of the nail bed. It may be caused by something as harmless as trauma to the nail, which causes a haemorrhage. This discolouration lasts until the nail grows out, so can be quite persistent. However, it can also be a sign of cancer, so it is essential to be aware of the symptoms and risks and consult with a doctor if necessary.
Melanonychia is often a harmless aesthetic problem caused by trauma that occurs to the tissues or skin under the nail bed. Although it is worrisome to some because the discolouration persists for a long time, the reason for this is simply that the melanonychia does not disappear until the nail grows out. Although melanonychia may be a symptom of melanoma, these melanonychia typically appear in multiple fingers/nail beds and/or are more persistent than benign melanonychias.
When most parts of your body suffer an impact, the metabolic enzymes in the body create a yellowish-green bruise. However, the nail beds do not have these metabolic enzymes. When bleeding or bruising occurs, it thus appears to be blackish brown, as blood under the nail bed. Typically, this grows out with the nail. However, if the cause of the discolouration is melanoma, a form of cancer, the melanonychia will usually be persistent and is not caused by a bruise or trauma, but instead by the melanoma itself.
Longitudinal melanonychia is a specific type of melanonychia that extends all the way from the cuticle (or even the lunula distal) and going to he end of the nail bed at your fingertips. This melanonychia typically appears with no trauma to the finger, and is a symptom of melanoma. If this melanonychia appears, you should consult with a physician for a diagnosis to rule out the cancerous condition.
Symptoms of Melanoma
Certain key patterns exist which make melanoma a more likely diagnosis as a cause of melanonychia. Doctors consider the number of fingers involved, since melanonychia on multiple fingers suggests that the melanonychia are caused by melanoma. The width of the discolouration is also important. If the width is wider at the beginning of the nail plate near the cuticle then at the end near the fingertips, this suggests that the lesion is evolving and may be indicative of melanoma. The specific colour is important, because melanomas typically have many different colour patterns, including irregular streaks in the pigment, while standard melanonychia are typically a more solid black/brown colour. Furthermore, a band of discolouration that is very dark and wide may also suggest that a melanoma is present. Discolouration on the cuticle and nail folds can also be a symptom of melanoma.
New medical knowledge and algorithms have helped to guide physicians in determining whether to biopsy melanonychia to check or melanomas. Typically, doctors begin with a medical history and physical exam. Doctors will examine the discolouration to identify a legion to be biopsied. If the doctor can determine that the legion is benign, then there is no need for a biopsy. If the legion is growing and/or a clear diagnosis can't be made, a biopsy is required. The biopsy will check for the presence of cancer cells to rule out melanoma.