What Should You Know About a Bluish Lump Under the Skin?

Blue or purple colour can come from blood close to the skin, blood trapped after an injury, or a vascular-looking lump. A tender, warm lump may occur with inflammation or a boil. Some skin lumps are deeper and painless. Less commonly, a persistent changing lesion may need assessment for a skin cancer such as basal cell carcinoma. Colour alone cannot identify the cause; the texture, mobility, duration and nearby skin provide useful clues.

Note when the lump appeared, whether it followed an injury or injection, and whether its size or colour is changing. Avoid squeezing, piercing or massaging it, because this can worsen bleeding or inflammation. Arrange a clinician’s examination if it remains, enlarges, becomes painful or is difficult to explain. The clinician may inspect it, feel its depth and decide whether imaging, drainage, biopsy or another treatment is appropriate.

Seek same-day medical advice for a rapidly enlarging lump, severe pain, spreading redness, warmth, pus, fever, numbness or colour change in the surrounding skin. Get urgent help if the lump follows significant trauma, bleeding does not settle, or you feel faint. A stable lump still deserves review if it does not resolve or keeps returning.

Ask whether the lump appears superficial or deep, what signs would make it urgent, and whether you need a scan or tissue sample. Discuss whether a boil, vascular lesion, cyst or other cause fits the examination, and ask which treatment is suitable if inflammation persists.