What should you know about giant pilar cyst?

Pilar cysts, also called trichilemmal cysts, develop in the outer covering of a hair follicle. They commonly occur on the scalp and may feel smooth, firm, and rounded beneath the skin. A large cyst can become noticeable while brushing, sleeping, wearing headwear, or changing a hairstyle. It may be harmless when quiet, but pressure, rubbing, or a break in the surface can lead to tenderness, redness, drainage, or inflammation.

The size of a lump does not establish its identity. A clinician may examine the scalp and the skin over the lump, then decide whether removal or laboratory examination is appropriate. Do not squeeze, pierce, or cut it at home; those actions can introduce infection and make later treatment harder.

Arrange a dermatology assessment if the lump is enlarging, repeatedly irritated, difficult to clean around, or affecting comfort. Until then, protect it from combs, helmets, and scratching. Keep the scalp clean with a gentle cleanser, and avoid applying harsh chemicals or unprescribed steroid or antibiotic products over a closed lump.

If removal is advised, the clinician will discuss local anaesthetic, the incision, care of the wound, and whether the cyst wall should be removed to reduce the chance of it returning. Read more about [Cyst Removal](/treatments/surgical-dermatology/cyst-removal/) and related [Skin Lumps](/symptoms/skin-lumps/).

Seek prompt medical care if the scalp becomes increasingly painful, hot, swollen, or red, or if pus, bleeding, fever, or a rapidly changing surface develops. Urgent assessment is appropriate for severe pain, spreading redness, marked swelling, or feeling unwell. These changes can signal inflammation or infection and are not a reason to attempt home drainage.

Ask whether the lump has features of a pilar cyst, whether it is inflamed, whether removal is recommended, how the wound will be closed, and what changes should prompt a review.