A blue nevus is a small patch of bluish discoloration on the skin, and it usually is benign. In some cases, however, these growths can become malignant and might develop into melanoma — or melanoma appears to be a blue nevus at first and then reveals its true colors. A doctor might note nevi, moles and other growths in a patient's chart to make it possible to track them over time. If the doctor notices changes, he or she can recommend a closer look to evaluate the patient for signs of cancer.
Blue nevi are often quite small, and they might sit at the surface of the skin or be slightly elevated. Some are so dark that they are almost black, and others are more faded. The growth can appear anywhere on the body, and it appears to be the result of an innocent mistake during embryonic development that leads to the formation of a cluster of melanocytes, the pigmented cells that cause skin to appear darker. The growth should remain stable in shape, size and position over time.
Parents might notice a blue nevus on a baby at an early age. A pediatrician can look at the growth and determine whether it is a health issue. At other times, a blue nevus might not become apparent until later in life. The sudden appearance of something that looks like a blue nevus is a cause for concern, because this might be a malignant melanoma rather than a harmless skin discoloration. If a patient is not sure about the origins of a growth, he or she might choose to err on the safe side and go to a doctor for a quick examination.
In an atypical cellular blue nevus, the cells are unusual in nature, which indicates that they might become cancerous. A doctor can determine whether a nevus is a cause for concern with a small scraping of the cells for evaluation under a microscope. If a pathologist identifies a problem, the patient has two options. One is to have the growth excised immediately to prevent the development of cancer. The other is simply to monitor the blue nevus for signs of change and to act if it becomes necessary.
If a blue nevus is a cause for concern and a doctor recommends monitoring it, he or she might take a photograph for reference. This can be useful if the doctor and patient are not sure about changes in size or shape. Any changes are a cause for concern and call for further examination.