If you notice a lump on the back of your head, don't get too worried right away. It doesn't necessarily mean something serious. Lumps on the head can be caused by a few different things. You may just accidentally bump into something. If it happens to you, take a deep breath and read on for more information and when to be concerned.

What Is the Lump on the Back of My Head?

You don’t really think about the back of your head much until there is something different there. At some point you may be brushing your hair and notice something.

1. Lipoma

Lipomas are tumors made up of fat cells. They grow a hard capsule on the outside which makes them feel like a hard lump. The cause is unknown, but is possibly genetic.

• Symptoms: Soft and doughy lump. Usually small, but can grow larger over time. There might be some pain as the lipoma grows.
• Treatments: The good news about lipomas is they are benign and nothing to worry about. However, they can grow and become a cosmetic issue. No treatment is necessary unless they grow to a size where they affect the appearance.

2. Sebaceous Cyst

These are small bumps that are caused by your sebaceous glands getting clogged. They are most often harmless and nothing to worry about, but any cyst should be checked by a doctor if it changes in size, shape, or appearance.

• Symptoms: The bump may drain fluid and dry to a crust. You may notice scalp flakes in the area. The cyst may close off and turn into a hard bump. They can become inflamed with redness, swelling, and pain.
• Treatment: If the cyst becomes a concern, the doctor will numb the area and remove the cyst. It will most likely be sent for biopsy, but they are often benign lesions. Keep your head clean and dry. Even if you are bald, use a good scalp brush to help keep the pores clear.

3. Ingrown Hair

What is that lump on the back of my head? You ask. It may just be ingrown hair. An ingrown hair occurs after a hair is shaved or breaks off. The hair continues to grow into the skin near the follicle. This condition is more likely to occur in men who shave their heads. These need to be watched for signs of infection.

• Symptoms: Painful lump that erupts like a pimple, redness and swelling.

4. Gout (Tophi)

Gout is a condition where the uric acid levels rise in your blood. It is a type of arthritis that also causes joint pain. The uric acid can form crystals that are deposited in your body called, tophi. You can develop tophi in places like earlobes, fingers, head, and near the joints. They can be painful and usually resolve as the uric acid levels drop.

• Symptoms of gout include painful joint or joints, swelling and redness in the affected area, fever, and trouble walking or using limbs that are affected. Tophi can appear after gout becomes chronic. It can also cause kidney stones.
• Treatment is aimed at reducing the uric acid levels. Eating a diet low in animal proteins (Purines), avoiding alcohol, and increasing fluids is very important. The doctor can give medication that helps flush uric acid from the body. 

5. Pilar Cyst

These cysts form around your hair follicles. They are basically just keratin, the same material that grows into hair. They most often affect the scalp, but on rare occasion they may be found on other areas of the body. Doctors do usually prefer to remove these cysts to prevent them from forming tumors. There is a rare risk of cancer with these cysts.

• Symptoms include hard lump on scalp, inflammation, and pain. The lump can become very hardened. This is because keratin is the same material that forms horns, although this would be very rare even in humans.

6. Basal Cell Carcinoma

On the very top layer of your skin or epidermis, there are basal cells. A lesion can develop on your skin and cause these cells to grow too rapidly. How did I get that lump on the back of my head? You may ask. It may be too much sun. BCC can be caused by sun exposure and people with light, thin, or no hair may be at a higher risk.

• Symptoms: Basal cell carcinoma may form a small lump on your head. It may also cause open sores and lesions. You may develop a red patch or even just a scar over the area. It is important to have these symptoms checked as soon as you notice. This cancer is slow growing, but still needs to be removed.

7. Lyme Disease

Lyme disease results from the bite of an infected tick. Ticks live in trees and sense our oxygen from our breath. They call drop from the tree onto your head and deliver a bite you’re not even aware of. This can swell into a lump over the next 72 hours.

• Symptoms of Lyme disease include fever, joint pain, “bulls-eye” rash at the site of the bite, nausea, and headache.
• Treatments: Lyme disease must be treated promptly with antibiotics or it can have long-term complications.

When to Worry about Bump on Back of Head

If you notice a lump on the back of your head, keep an eye on it. Watch it closely for changes like:

• Growth of the lump
• Pain level increases
• Turns into open sore
• Bleeding

If there is an increase in pain or the lump gets larger, you need to contact your doctor for an evaluation. Most cysts and lumps are benign and nothing to worry about, but the above signs could signal malignancy. Certain types of skin cancer are slow growing so your doctor may opt to “watch and wait” to see if the lesion changes. You may also need to have a biopsy, where the doctor takes a small sample of tissue to check things out.