Most lumps under the skin are not cause for concern. The glands (lymph nodes) on either side of the neck, under the jaw, or behind the ears commonly swell when you have a cold or sore throat. More serious infections may cause the glands to enlarge and become very firm and tender. Glands can also swell and become tender after an injury, such as a cut or bite, or when a tumor or infection occurs in the mouth, head, or neck. Swollen glands and other lumps under the skin can be caused by many different things, including illness, infection, or another cause.
Swollen glands commonly develop when the body fights infections from colds, insect bites, or small cuts. More serious infections may cause the glands to enlarge and become firm, hard, or tender. Examples of such infections include:
- Bacterial infections, such as:
- A boil (abscess), similar to a large pimple. A boil may develop when a hair follicle or the skin becomes infected. A sweat gland abscess may form one or more lumps in the armpit that look like boils.
Noncancerous (benign) growths
Types of noncancerous (benign) growths, which are usually harmless, include:
- A lipoma, a smooth, rubbery, dome-shaped lump that is easily movable under the skin.
- A cyst, a sac of fluid and debris that sometimes hurts.
- Cystic lesions from acne are large pimples that occur deep under the skin.
- Branchial cleft cysts are found in the neck and do not usually cause problems unless they become infected. These cysts are most common in teenagers.
- An epidermal cyst (also called a sebaceous cyst) often appears on the scalp, ears, face, or back.
- A ganglion is a soft, rubbery lump (a type of cyst) on the front or back of the wrist.
- An inflammation of fatty tissue under the skin (erythema nodosum) or overgrown scar tissue (keloid).
Hernias, aneurysms, or nodules
Hernias or aneurysms are bulging sections in a muscle or blood vessel. A nodule is usually a growth on a gland. A hernia, aneurysm, or nodule may be felt under the skin but may not be visible. These types of lumps may need more medical evaluation.
- An inguinal hernia is a soft lump in the groin or near the navel. It may be more visible when you cough. Hernias that disappear when you press on them may not need any treatment. Hernias that don’t disappear when you press on them may be more serious and need medical treatment.
- A bulging section in the wall of a blood vessel (aneurysm) may feel like a pulsating lump in the abdomen, in the groin, or behind the knee. It can cause serious problems if it involves the blood vessels in the brain or the abdomen. Aneurysms may be a medical emergency and may require immediate evaluation.
- A thyroid nodule is an abnormal growth on the thyroid gland. An enlarged thyroid gland (goiter) is in the neck just below the Adam’s apple.
Swelling caused by cancer
A lump caused by cancer is usually hard, irregularly shaped, and firmly fixed under the skin or deep in tissue. Although they usually do not cause pain, some types of cancerous lumps are painful. Most lumps are not caused by cancer.
Swelling may also be caused by:
- A side effect of a medicine, such as phenytoin (Dilantin).
- Other medical conditions and diseases, such as lupus, chronic fatigue syndrome, or rheumatoid arthritis.