Dark bumps on the skin may be caused by dermatofibroma, nevus nigricans, melanoma and other causes.
1. Dermatofibroma: it is caused by excessive proliferation of fibroblasts producing extracellular matrix, which can lead to the appearance of localized small bumps, the color is often heavier, may be brown, due to differences in skin color may be manifested as black.
2. Nevus melanosus: it is a benign proliferation of melanocytes, in which the nevus cells of intradermal nevus are located in the subepidermal layer of the dermis, often higher than the surface of the skin, which can be manifested as black and black bumps, usually with no obvious uncomfortable symptoms, but there may be a slow increase in the size of the nevus.
3. Melanoma: it is a kind of tumor caused by malignant change of melanocytes, its early appearance is similar to that of nevus, and it tends to have higher degree of malignancy, and its condition may continue to aggravate if it is not treated in time.
Skin long black bumps may also be caused by other reasons, if a short period of time to change faster, should be timely to the hospital dermatology department to find out the cause of the treatment as prescribed by the doctor.