What should you know about blue nevus melanoma?

A blue nevus is a usually benign mole whose colour comes from pigment deeper in the skin. Melanoma can also look blue, blue-black, grey, or uneven because of pigment at different depths. Colour alone cannot distinguish them. A dermatologist may examine the lesion with dermoscopy and compare it with earlier photographs. If the appearance is concerning, removing the whole lesion or taking a suitable biopsy allows a laboratory to examine the cells.

A melanoma diagnosis is based on the examined tissue, followed by assessment of features such as depth and ulceration. This information guides whether further surgery, a sentinel lymph node biopsy, scans, or medicines such as immunotherapy should be discussed.

Arrange a skin examination if the blue spot is new, changing, growing, bleeding, crusting, itching, or different from your other moles. Do not scratch it, attempt to remove it, or rely on home photographs as a diagnosis. Take a clear photograph beside a ruler and note when you first noticed the change. A clinician may recommend surgical excision when the lesion cannot be confidently identified by examination alone.

If melanoma is confirmed, treatment depends on the lesion and any evidence of spread. Options can include skin cancer surgery, tumour removal surgery, and specialist follow-up after treatment.

Seek prompt medical review for a rapidly changing blue or black lesion, bleeding without a clear injury, an open sore that does not heal, marked asymmetry, or a new firm lump near the lesion. Seek urgent help for severe illness, uncontrolled bleeding, or new neurological symptoms such as weakness, confusion, or a seizure; these symptoms require immediate assessment and are not proof of melanoma spread.

Ask whether the lesion needs dermoscopy, biopsy, or complete removal; what features make it concerning; when results will be available; whether nearby lymph nodes need assessment; and what follow-up schedule fits your findings.