Common Benign Causes for Lumps on the Head
While finding a lump on your head can be worrying, many causes are harmless and temporary. These can include a range of skin conditions and minor injuries that resolve on their own with little intervention.
Cysts and Fatty Growths
Cysts and lipomas are among the most frequent causes of lumps under the skin, including on the back of the head.
- Pilar cysts: These are smooth, dense, and keratin-filled lumps that form around a hair follicle and typically appear on the scalp. They are usually painless and slow-growing. While generally harmless, they can be surgically removed if they cause discomfort or for cosmetic reasons.
- Epidermoid cysts: Similar to pilar cysts, these are benign, fluid-filled sacs that can develop under the skin due to a buildup of keratin. They often have a visible central opening and are the most common type of cutaneous cyst.
- Lipomas: A lipoma is a soft, fatty, noncancerous growth that develops just beneath the skin. They are often described as rubbery and can move when you press on them. They are typically painless and don't require treatment unless they grow very large or are bothersome.
Swollen Lymph Nodes
The occipital lymph nodes are located at the base of the skull, and they swell when fighting an infection. A swollen lymph node often feels like a firm, movable lump that may be tender to the touch.
- Causes for swelling can include scalp infections, head lice, viral infections like rubella, or bacterial skin infections from a wound.
- The swelling typically resolves once the underlying infection is treated or clears up.
Scalp and Hair Follicle Issues
Conditions affecting the hair follicles and skin on the scalp can also result in localized bumps.
- Folliculitis: An inflammation or infection of the hair follicles, which can cause red or pus-filled bumps that resemble acne.
- Scalp acne: Like acne elsewhere on the body, this occurs when hair follicles become clogged with skin cells and sebum.
- Ingrown hairs: If you shave your head, a hair can grow back into the skin, causing a small, inflamed bump.
Injury or Trauma
A blow to the head is a common cause of bumps, often resulting in a scalp hematoma or “goose egg”. This is a collection of blood under the skin that creates a semisolid bump. Minor head injuries can typically be treated at home with ice and rest, but serious injuries require medical attention.
Less Common and Concerning Issues
While rare, a lump on the back of the head can sometimes be a sign of a more serious condition.
Bone Spurs
Also known as osteophytes or exostosis, a bone spur is a hard, immovable bony outgrowth that can sometimes occur on the skull. They can be harmless but may cause pain if they press on surrounding tissue.
Skull Base Tumors
In very rare instances, a bump could be a sign of a bone tumor, such as a chordoma, which can grow at the base of the skull. Symptoms of larger tumors can include headaches, hearing problems, or difficulty with balance.
Skin Cancer
Certain types of skin cancer can appear as a lump, sore, or patch on the scalp. Though less common on the back of the head, prolonged sun exposure can increase risk, especially for those with thinning hair or who are bald.
How Lumps Are Diagnosed and Treated
Diagnosis of a head lump begins with a physical exam and medical history. Your doctor may ask about its appearance, any associated symptoms, and how long it has been present. Depending on their findings, they may recommend further testing.
- Diagnostic Imaging: Tests like CT scans, MRI, or X-rays can provide more information about the lump's size, location, and composition.
- Biopsy: A small tissue sample may be taken and examined in a lab to check for cancer cells.
- Blood Tests: These can help determine if an infection is causing swollen lymph nodes.
Treatment varies widely based on the cause. Many harmless lumps may be left alone or treated with at-home care. Infections are often treated with antibiotics, while cysts and some benign tumors may require surgical removal.
When to See a Doctor
Most lumps are not a cause for immediate alarm, but certain characteristics warrant professional medical evaluation. You should seek immediate attention if a lump appears after a severe head injury and is accompanied by symptoms like dizziness, confusion, nausea, or loss of consciousness.
For any other lump, it is important to contact a doctor if you observe any of the following:
- The lump is growing rapidly or getting worse.
- It is causing severe pain or other problems.
- It is warm to the touch or surrounded by redness.
- It produces pus or discharge.
- It is hard, irregular, and immobile.
- You experience associated symptoms like fever, unexplained weight loss, or night sweats.
Comparison of Lumps
| Feature | Benign Lump (Often) | Potentially Serious Lump (Rarely) |
|---|---|---|
| Consistency | Soft, mobile, rubbery (lipoma) or firm but movable (cyst) | Hard, fixed, and immovable |
| Growth | Slow-growing or stable over time; may fluctuate with hormones or infection | Grows steadily and noticeably over time |
| Appearance | Smooth, round, well-defined borders | Irregularly shaped, indistinct borders |
| Pain | Often painless, though can become tender or painful if infected | Pain can be present, especially if pressing on nerves |
| Associated Symptoms | May have redness, swelling, or tenderness if infected | May include fever, unexplained weight loss, night sweats, or neurological symptoms |
Conclusion
While the vast majority of lumps on the back of the head are benign, such as cysts, lipomas, or swollen lymph nodes due to infection, any persistent or concerning bump should be evaluated by a healthcare professional. Recognizing common, harmless causes can provide peace of mind, but understanding the warning signs is vital for addressing potential health issues promptly. Consulting a doctor for a proper diagnosis is the most important step for any unexplained lump. For further information on skull base tumors, which are a rare cause of head lumps, you can visit the Mayo Clinic website.
