Lipoma vs Sebaceous Cyst: What Is the Difference?

What is a lipoma?

A lipoma is a benign lump of fat cells in a thin capsule, usually just under the skin. It is soft or rubbery, moves slightly when pressed, and grows slowly. Lipomas are common on the shoulders, back, arms, neck and thighs, and some people develop several.

What is a sebaceous cyst?

A “sebaceous cyst” is usually an epidermoid cyst (or, on the scalp, a pilar cyst). It is a closed sac under the skin filled with a soft, cheesy material made by its lining. It feels firmer and rounder than a lipoma, is attached to the skin, and often has a small dark opening (punctum) on its surface. Cysts can become inflamed, red and painful, and may burst and discharge.

Lipoma vs sebaceous cyst at a glance

	Lipoma	Sebaceous (epidermoid) cyst
Made of	Fat cells	Sac filled with keratin material
Feel	Soft, rubbery, doughy	Firmer, round, smooth
Attachment	Moves under the skin	Attached to the skin
Surface	Normal skin	Often a small dark opening
Infection	Rare	Common; can become red and discharge
Smell	None	Contents may smell if released
Common sites	Shoulders, back, arms, neck, thighs	Face, neck, chest, back, scalp
Removal	Excision, sometimes liposuction	Excision of the whole sac

How does a doctor tell them apart?

Usually by examination alone: feel, depth, attachment to the skin and the presence of a punctum. An ultrasound is helpful when a lump is deep, large, hard or unclear. Lumps that are larger than about 5 cm, growing quickly, hard and fixed, deep under muscle, or painful are checked more carefully, sometimes with a scan before removal.

How is each one removed?

Lipoma: under local anaesthesia, a small cut is made over the lump and the lipoma is removed whole with its capsule. Selected soft lipomas can be reduced by liposuction through smaller openings. See lipoma removal.

Sebaceous cyst: under local anaesthesia, a small ellipse of skin including the punctum is removed with the whole sac. If the cyst is inflamed, it is usually treated first and removed a few weeks later, once it settles. See sebaceous cyst removal.

Both are sent to the laboratory to confirm the diagnosis.

What is recovery like after removal?

Time	What to expect
Day 1	Mild soreness; most people return to normal activities
Days 1-2	Keep the dressing dry
Days 5-14	Stitches removed: earlier on the face, later on the back
About 1-2 weeks	Laboratory report discussed
Months 3-12	The scar fades and softens

Avoid heavy lifting or stretching over wounds on the back and shoulders for about two weeks, as scars there tend to widen.

Can lumps be removed for appearance alone?

Yes. Many people choose removal because a lump is visible, catches on clothing or simply bothers them, even when it is harmless. Removal for appearance is usually considered cosmetic by insurers, while removal of a painful, growing or uncertain lump is more likely to be treated as medical care. Several lumps can often be removed in one sitting under local anaesthesia.

Myths about lumps under the skin

• “A cyst can be squeezed out for good.” The sac remains and refills.
• “Lipomas melt with weight loss.” They usually stay the same size.
• “Every lump must be removed.” Many can be safely watched once diagnosed.
• “Antibiotics cure a cyst.” They treat infection but leave the sac.

When should you see a doctor?

See a doctor about any new lump, and sooner if it is growing, hard, fixed, painful, red and hot, or larger than about 5 cm. A lump in the armpit, breast or groin should also be checked promptly.

What should you ask?

• Is this a lipoma, a cyst or something else?
• Does it need a scan before removal?
• Should an inflamed cyst settle before surgery?
• How long will the scar be?

For more on many lipomas at once, read multiple lipomas, and for removal details see lipoma removal.