What causes a lump on your skull? Understanding the possibilities

According to health data, most head lumps are benign and resolve on their own, often caused by minor trauma or skin conditions. This guide will help you understand what causes a lump on your skull and when it might be necessary to seek medical advice.

Quick Summary

A lump on your skull is most commonly caused by minor injuries, skin cysts (like pilar or epidermoid cysts), benign fatty growths (lipomas), or inflamed hair follicles (folliculitis). Though usually harmless, any persistent or concerning lumps should be evaluated by a healthcare professional to rule out rare serious conditions.

Key Points

• Common Causes: The most frequent causes of skull lumps include injuries, cysts, lipomas, infections, and inflamed hair follicles.

• Texture Matters: The feel of a lump can offer clues—soft and rubbery for a lipoma, firm and mobile for a cyst, or hard and immobile for a bone spur.

• When to See a Doctor: Seek professional advice for any new or changing lump, if it grows rapidly, becomes painful, or if you experience associated symptoms like severe headaches or dizziness.

• Benign is Most Common: Most skull lumps are harmless and non-cancerous, and many do not require treatment.

• Diagnosis is Key: A doctor will determine the cause through a physical exam and may use imaging or a biopsy for a definitive diagnosis.

• Treatment Varies: Treatment options range from simple observation to surgical removal, depending on the lump's type and symptoms.

Common Causes of Lumps on the Skull

Finding an unexpected bump on your skull can be a source of worry, but the majority of cases can be attributed to common, benign conditions. Identifying the characteristics of the lump—such as its texture, location, and associated symptoms—is key to understanding its potential cause. While serious conditions are rare, a doctor's evaluation is always recommended for new or changing growths.

Injuries and Scalp Trauma

One of the most frequent causes of a head lump is a direct injury. A blow to the head can cause a collection of blood under the scalp, forming a hematoma, which is often called a 'goose egg.'

• Scalp Hematoma: A swollen, bruised lump that is tender to the touch. It typically appears immediately after an injury and resolves over days or weeks as the body reabsorbs the blood.
• Head Injury: More severe trauma can result in larger or more painful bumps. In these cases, it is crucial to monitor for symptoms of a concussion, such as dizziness, nausea, memory loss, or loss of consciousness.

Cysts: The Most Common Type of Growth

Cysts are non-cancerous sacs filled with fluid or semi-solid material. They are very common on the scalp and face and are typically harmless unless they become infected.

• Pilar Cyst: These are the most common type of scalp cyst, growing from hair follicles. They are usually smooth, firm, and skin-colored, moving freely under the skin. They are filled with keratin and rarely cause pain unless infected.
• Epidermoid Cyst: These cysts also contain keratin and develop from skin cells trapped beneath the surface. They can occur anywhere, including the scalp, and sometimes have a small, dark plug on the surface.

Benign Skin and Fatty Growths

Another common cause of a lump is the overgrowth of non-cancerous tissue.

• Lipoma: A benign fatty tumor that feels soft, rubbery, and can be moved slightly with your fingers. Lipomas are slow-growing and typically painless, rarely appearing on the head but possible.
• Seborrheic Keratosis: A non-cancerous skin growth that can look waxy, scaly, or like a mole. They are common in older adults and often feel rough or slightly raised.

Infections and Inflammation

Inflammatory conditions affecting the skin and hair follicles can also lead to lumps.

• Folliculitis: The infection of a hair follicle, leading to red, sore, pus-filled, or pimple-like bumps. It can be caused by bacteria or fungi.
• Abscess: A painful, swollen lump filled with pus that forms when bacteria enter the skin. The area around it is often red and warm.
• Swollen Lymph Nodes: Lymph nodes behind the ears or at the base of the skull can swell in response to infections like a cold, flu, or ear infection. These lumps are typically soft, mobile, and tender.

When a Skull Lump Could Be Serious

While most lumps are not a cause for concern, it is vital to recognize the rare signs that may indicate a more serious underlying condition. These conditions are far less common but require prompt medical attention.

Bone Spurs (Osteomas)

A bone spur is a bony growth that forms on existing bone. On the skull, an osteoma can feel like a hard, immovable lump.

• They are typically painless and grow very slowly.
• Osteomas are almost always benign but should be checked by a doctor to confirm the diagnosis.

Malignant (Cancerous) Growths

In very rare cases, a lump on the skull or scalp can be cancerous. This may involve skin cancer or a tumor that has spread from elsewhere.

• Basal Cell or Squamous Cell Carcinoma: Types of skin cancer that can present as a non-healing sore, a red scaly patch, or a pearly-white lump.
• Skull or Brain Tumors: Extremely rare, but they can cause symptoms beyond the lump itself, such as vision changes, headaches, or neurological issues.

Comparison of Common Skull Lumps

Feature	Hematoma (Goose Egg)	Cyst (Pilar/Epidermoid)	Lipoma	Bone Spur (Osteoma)
Cause	Head trauma/injury	Blocked hair follicle/skin pore	Fatty tissue growth	Bone overgrowth
Texture	Firm, tender, bruised	Firm, smooth, mobile	Soft, rubbery, mobile	Hard, immobile
Onset	Sudden, after injury	Gradual, slow-growing	Gradual, slow-growing	Gradual, slow-growing
Pain Level	Usually tender/painful	Typically painless (unless infected)	Painless	Usually painless
Redness	Common	Possible (if infected)	Rare	Rare

Diagnosis and Treatment

If you find a lump on your skull, the first step is to see a healthcare professional for an accurate diagnosis. The diagnostic process may involve a physical exam, taking a medical history, and potentially imaging or a biopsy.

1. Physical Examination: A doctor will physically examine the lump, noting its size, shape, color, and how it feels to the touch.
2. Medical History: They will ask about when the lump appeared, its rate of growth, any associated symptoms, and any recent injuries.
3. Imaging: For more detailed assessment, a doctor may order an ultrasound, CT scan, or MRI.
4. Biopsy: A small tissue sample may be removed and examined under a microscope to confirm if the lump is benign or cancerous.

Most benign lumps do not require treatment unless they are causing discomfort or for cosmetic reasons. Treatment may involve:

• Observation: For harmless lumps like small cysts or lipomas, a "watchful waiting" approach is common.
• Surgical Excision: Removal of the lump, often a simple outpatient procedure, for larger or symptomatic cysts, lipomas, or osteomas.
• Medication: Antibiotics for infected lumps like abscesses or folliculitis.

For more complex or serious conditions, a specialized treatment plan will be developed in consultation with specialists.

Final Thoughts and Outlook

Discovering a lump on your skull can be frightening, but the overwhelming odds are that it is a benign condition. Common causes such as minor trauma, cysts, and benign growths account for the vast majority of cases. However, any new, changing, or painful lump should be evaluated by a healthcare provider for proper diagnosis and peace of mind. Early assessment is key to addressing any potential issues promptly and effectively. Consulting with a professional can provide clarity and ensure that any necessary treatment is received. For reliable medical information, always refer to reputable sources such as the Mayo Clinic, which provides extensive resources on various conditions affecting the skull and skin, including information on tumors and cysts. Mayo Clinic.

Frequently Asked Questions

Can a lump on my skull be a sign of a brain tumor?

A lump on the skull is very rarely a brain tumor. Most skull lumps are located in the scalp or skull bone itself, not the brain. While it's a valid concern, the probability of a benign cause is much higher.

What is the difference between a cyst and a lipoma on the scalp?

A cyst, like a pilar cyst, is a sac filled with keratin and often feels firm and mobile. A lipoma is a benign fatty tumor that typically feels soft, rubbery, and movable beneath the skin.

Should I be worried about a lump that appears after hitting my head?

Bumps from minor head injuries, often called 'goose eggs,' are common hematomas and usually resolve on their own. However, seek immediate medical attention if you experience symptoms like loss of consciousness, severe headache, confusion, or vomiting.

How long does a lump on the skull typically last?

The duration depends on the cause. A bump from an injury might go away in a few weeks, while cysts and lipomas can persist for months or years. If a lump lingers or grows, a doctor's visit is warranted.

Is a hard lump on the back of my skull always a bone spur?

A hard, immobile lump could be a bone spur, or osteoma, which is a benign bone growth. However, only a doctor can provide an accurate diagnosis, as it can sometimes be confused with other conditions.

Can scalp acne cause a lump on the skull?

Yes, an infected hair follicle, or folliculitis, can cause a painful, pus-filled bump on the scalp that may resemble a pimple. These are typically smaller and less firm than cysts or bone spurs.

When should a lump on the skull be surgically removed?

Surgery may be recommended for cosmetic reasons, if the lump is growing rapidly, is painful, or if there is any suspicion of malignancy. Many benign lumps are simply monitored and left untreated.