A lump behind the ear can have many potential causes, including acne, cysts, and infections. Swollen lymph nodes and certain cancers can also cause lumps. It is best to contact a doctor for advice if a lump develops.

In some cases, the lump may not cause any other symptoms, and it may resolve on its own. However, depending on the cause, medical treatment may also be necessary.

This article discusses the possible causes of a lump behind the ear, when to seek medical advice, and how doctors diagnose the cause of the lump.

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Acne is a common skin condition that most commonly affects the face. It might also cause a lump behind the ear, near the face.

With acne, pores in the skin become blocked with sebum. Sebum is an oily substance secreted by glands at the base of hair follicles. The sebum mixes with dead skin cells and can form a layer called a comedone.

A pimple might become infected and inflamed if certain bacteria enter the comedone.

Inflamed pimples can grow and, in their most severe form, create lumps called acne cysts.

If the lump is due to acne, pressing on it may cause pain.

Treatments for acne include:

  • topical medications such as antibiotics and retinoids
  • oral antibiotics
  • hormone therapy
  • photodynamic therapy
  • chemical peels

A person’s doctor can advise on what treatments they recommend for acne.

Learn more about acne.

A cyst can occur anywhere in the skin, including behind the ear.

Skin cysts are fluid-filled sacs. They form a raised, dome-shaped area on the skin. Sometimes, they have a black spot called a punctum at the top.

Cysts can typically move around freely if a person tries to move them.

Epidermoid cysts are most likely to develop around the face, neck, and trunk, but they can develop anywhere on the body. These form on the glands responsible for the oily substance that moisturizes the skin and hair.

Learn more about cysts.

Lipoma is another possible cause of lumps behind the ear. Lipomas are benign fatty lumps that can grow anywhere there are fat cells.

They are more common on other parts of the body, namely the trunk, but can occur anywhere under the skin, including behind the ear.

A lipoma feels soft to the touch. It is not usually tender or painful unless it presses on nearby nerves.

Cosmetic surgeons can remove lipomas, though treatment may not be necessary. A person’s doctor can advise on whether they recommend removing the lipoma lump and answer any questions a person may have.

Learn more about lipoma.

The lymph nodes are part of the immune system that help filter and drain foreign substances. They grow in various locations throughout the body, including behind the ear.

The lymph nodes behind the ear are called the posterior auricular lymph nodes.

A lymph node can swell for a number of reasons, including:

  • infection
  • skin conditions
  • dental issues
  • cancer

Treatments for swollen lymph nodes can depend on the underlying cause.

Learn more about swollen lymph nodes.

Mastoiditis is a bacterial infection affecting the mastoid. The mastoid is the part of the skull bone behind the ear.

The infection develops in the air spaces of the bone. The mastoid has a honeycomb-like structure. Bacteria can enter and infect these air cells.

Mastoiditis is more common in children than adults. It is a serious infection that needs medical attention. The swelling behind the ear will usually be tender and might cause the ear to push outward.

Other symptoms may go with the lump, including:

A person is more likely to develop mastoiditis if they have a severe ear infection or frequent ear infections.

A doctor will usually prescribe antibiotics to treat the infection. An ear, nose, and throat (ENT) doctor may treat some cases with surgery to drain or remove the infection.

Learn more about mastoiditis.

Although uncommon, a lump behind the ear can indicate cancer. This includes salivary gland cancer.

A cancerous lump is usually:

  • firm to the touch
  • irregular or uneven in shape
  • fixed in place if a person tries to move it

It is important to contact a doctor as soon as there are concerns about a lump. The doctor will be able to perform a physical examination and order tests to confirm the diagnosis.

It is important to contact a doctor if a person develops a new lump or if there are changes to an existing lump.

It is especially important to contact a doctor about a lump if it:

  • is painful
  • has discharge
  • is fixed in place
  • changes or grows
  • appears suddenly
  • accompanies more general symptoms

To assist with reaching an accurate diagnosis, a doctor may begin by examining the appearance and texture of the lump.

They may then ask a range of questions about a person’s symptoms and take a full medical history.

In some cases, the doctor may order tests to confirm a diagnosis. This might include an ultrasound scan or a biopsy. A biopsy involves removing a sample of tissue for analysis in a laboratory.

The doctor will be able to advise on any tests they order and answer any questions a person may have.

There are numerous possible causes of a lump behind the ear. Examples include acne, an infection, cysts, and swollen lymph nodes.

In some cases, a lump behind the ear may be cancerous. A cancerous lump is typically firm to the touch and fixed in place. It may also be painful and produce discharge.

It is best to contact a doctor as soon as a person notices a new lump or experiences changes in an existing lump. The doctor will be able to perform an examination, and they may order tests to reach an accurate diagnosis.

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