A large, dark, rounded growth on the back can look alarming, especially when the surrounding skin appears swollen and irritated. The image shows a prominent raised lesion on the upper back surrounded by an area of redness, with a medical professional preparing the skin for treatment.

While the exact diagnosis cannot be confirmed from a photograph alone, lesions like this can sometimes be associated with epidermoid cysts, inflamed cysts, or other types of skin growths. Epidermoid cysts commonly occur on the trunk and can become painful, swollen, or inflamed. Most are harmless, but they can become inflamed, rupture, or become infected, leading to redness, tenderness, and swelling.

Inflammation can cause the skin around a cyst to become red, swollen, and tender. Importantly, redness does not always mean that an epidermoid cyst is infected. The American Academy of Dermatology notes that many red and swollen epidermoid cysts are inflamed rather than infected. This distinction matters because treatment depends on the underlying problem.

When a cyst is large, painful, repeatedly irritated, or inflamed, a dermatologist or other qualified healthcare professional should determine the appropriate treatment. Possible options include incision and drainage, medication or injection to reduce inflammation, or complete surgical removal when appropriate. It may be tempting to squeeze, puncture, or cut a large lump at home, but this can increase the risk of infection, bleeding, tissue injury, and scarring.