Pilomatrixoma

A pilomatrixoma (also called a pilomatricoma or calcifying epithelioma) is a benign lump that develops from the cells at the base of a hair follicle. Over time the lump often becomes hard as calcium is deposited within it.

It appears as a firm, sometimes stony-hard nodule just beneath the skin, usually on the head, neck, face or upper arms. The overlying skin may look normal or have a bluish or reddish tinge, and the lump can feel slightly irregular or angular under the fingers. Pilomatrixomas are common in children and are not cancerous.

Pilomatrixomas do not disappear on their own and tend to grow slowly over months or years. They may become tender, be knocked during play, or occasionally become inflamed or break through the skin.

• Removal is recommended to:
• Confirm the diagnosis by examining the tissue under a microscope
• Prevent the lump from enlarging and becoming more noticeable
• Avoid the lump becoming irritated, infected or ulceratedThe diagnosis can usually be made by examination alone, though an ultrasound is sometimes arranged. There is no urgency, and surgery is scheduled at a time that suits your family.

The operation is performed under a general anaesthetic as day surgery. Local anaesthetic is added to the area to keep your child comfortable after waking.

An incision is made over the lump, placed along a natural skin line wherever possible to keep the scar as fine as it can be. The lump is removed together with a small margin of the overlying skin if it is attached, as this reduces the chance of it coming back. The skin is closed with fine dissolving stitches and covered with a dressing or skin glue. The tissue is sent to the laboratory to confirm the diagnosis.

Discomfort is usually mild and settles with simple pain relief within a day or two. Your child can return to school or daycare once they feel well, usually within a few days, avoiding contact sport until the wound has healed.

Keep the wound clean and dry for the first couple of days. Scars are pink and slightly raised at first and fade gradually over many months; protecting the area from the sun helps it settle. Contact the team if there is fever, increasing redness or discharge. The laboratory result and wound are reviewed at a follow-up appointment.