Cyst in the leg under the skin: what to know

An epidermoid cyst is a pocket beneath the skin that can contain keratin, a thick material made by skin cells. It may feel round, smooth, and movable, and it can remain quiet for a long time. Tight clothing, shaving, friction, or an injury may make it irritated. The term sebaceous cyst is often used casually, although the lump may not arise from an oil gland.

A leg lump can also be an abscess, lipoma, swollen node, or another growth. A clinician may inspect it and assess depth, movement, tenderness, and skin changes rather than relying on a photograph.

Do not squeeze, lance, or repeatedly press the lump. Keep the skin clean, reduce rubbing, and cover it lightly if clothing irritates the surface. Arrange a medical review for a persistent, enlarging, or recurrent lump. If it is inflamed, a clinician may discuss a steroid injection into the skin in selected situations, although that is not suitable for every lump.

A painful collection of infected material may need abscess drainage. For a recurring or bothersome cyst, cyst removal may be discussed; ask whether the cyst wall can be addressed as well as its contents.

Seek prompt care for a hot, red, rapidly swelling, or increasingly painful leg lump, especially if pus or blood is draining. Fever, chills, red streaking, or feeling unwell may indicate infection. Urgent assessment is appropriate for severe pain, marked swelling, skin discoloration, sudden change, or difficulty walking.

Ask what the lump most closely resembles, whether it needs imaging or observation, and what changes should prompt review. If a procedure is proposed, ask about numbing, dressing changes, activity limits, scarring, and how recurrence would be handled.