A skin lump that repeatedly becomes swollen, leaks material or returns after settling may be a cyst. Epidermoid and pilar cysts contain keratin within a sac beneath the skin. They are usually benign, but rupture or infection can cause pain, redness and unpleasant-smelling discharge. Treating only the contents may relieve pressure without removing the cyst wall, allowing the problem to recur.

Typical symptoms

A cyst often feels like a round, smooth lump attached to the skin. Some have a small central opening. It may remain stable for years before enlarging or becoming inflamed. Discharge can be thick, pale and strong-smelling. When infected, the area may become hot, red and painful or form an abscess.

Why does it keep returning?

A cyst can refill when its lining remains beneath the skin. Squeezing may empty some material but can rupture the wall, trigger inflammation and make later removal more difficult. Incision and drainage treats an acute collection but is not always a definitive cyst removal. Other recurrent discharging conditions, including pilonidal disease or hidradenitis, require a different approach.

Assessment and diagnosis

Your surgeon will examine the location, size, skin opening and any previous scar. Ultrasound may be useful for an uncertain or deeper lump, although many cysts are diagnosed clinically. A persistently ulcerated, rapidly growing or unusual lesion may need biopsy or referral. Removed tissue is often sent for histology to confirm the diagnosis.

Treatment options

A quiet, uncomplicated cyst can be removed with its wall through a minor surgical procedure. If it is acutely infected, drainage or antibiotics may be needed first, with definitive excision after inflammation settles. Excision leaves a scar and carries risks of bleeding, infection, delayed healing and recurrence if any cyst wall remains.

When to seek urgent advice

Prompt assessment is needed if pain or redness is increasing, pus is spreading, you develop fever or the swelling is on the face near the eye. Do not attempt to cut, pierce or repeatedly squeeze a cyst at home.

Frequently asked questions

Why does my cyst smell? Keratin within a cyst can have a strong odour, especially if the cyst ruptures.

Can a cyst disappear without treatment? Inflammation may settle, but the cyst lining often remains and can refill.

When is the best time to remove it? Complete excision is usually easier when the cyst is not acutely inflamed or infected.