A lump on the head, often called a cyst, is a closed sac under the skin filled with fluid, keratin, or gas. Most common external cysts found on the scalp are benign and do not cause true headaches, though they can cause localized pain or discomfort. Headaches only result when these masses grow large enough to cause physical pressure or when they become inflamed or infected. The specific location and nature of the cyst determine its potential to create head pain, requiring a distinction between masses on the outer scalp and those developing inside the skull.
External Cysts of the Scalp and Headache Potential
The most frequent lumps found on the scalp are pilar and epidermoid cysts, which are slow-growing sacs filled with keratin that originate from hair follicles. These masses are usually soft or firm and often remain painless for years. A scalp cyst primarily causes pain when it undergoes an inflammatory event, such as infection or rupture, causing swelling and tenderness in the surrounding tissue. This inflammation leads to localized discomfort that can be perceived as a headache radiating from the point of infection.
A cyst’s physical size and placement can also mechanically irritate nearby structures or nerves. A large cyst situated over a bony area or near a major sensory nerve might cause pain when the head rests on a pillow or during routine activities like brushing hair. This constant, localized pressure on the scalp tissue can trigger a type of head pain or cause referred pain due to nerve irritation.
Mechanisms Linking Cysts to Head Pain
The connection between a cyst and head pain depends on two mechanisms: the body’s inflammatory response and the physical effect of the mass itself. When a cyst becomes infected, the body initiates an inflammatory cascade, releasing chemicals that sensitize local nerve endings and cause tissue swelling. This neurogenic inflammation directly causes pain, converting a silent lump into a tender source of discomfort. This pain is localized directly to the cyst site and its immediate surroundings.
Beyond inflammation, any growing mass can induce head pain through mass effect or traction. While brain tissue lacks pain receptors, surrounding structures like the dura mater (the outer membrane covering the brain) and the periosteum (covering the skull bone) are richly supplied with pain-sensitive nerves. A cyst that grows large enough to exert pressure on these structures or on intracranial vessels can trigger a headache. Localized irritation of peripheral nerves, such as the occipital nerve, can also result in referred pain perceived broadly across the head.
Recognizing Signs of Internal Cysts
It is important to distinguish a visible, benign scalp cyst from a deeper, internal, or intracranial cyst. Intracranial cysts, such as arachnoid or colloid cysts, are fluid-filled sacs within the brain or its surrounding membranes. These are more likely to cause severe headaches because they can disrupt the flow of cerebrospinal fluid (CSF), leading to increased intracranial pressure. Headaches caused by increased pressure are often distinct, typically becoming worse in the morning or after lying down, and may be exacerbated by coughing or straining.
A severe, progressive headache accompanied by neurological symptoms serves as a red flag indicating the need for prompt medical evaluation. Warning signs include persistent nausea and vomiting, sudden changes in vision or hearing, or problems with balance and coordination. A colloid cyst can cause intermittent, severe headaches that change with head position due to temporary obstruction of CSF flow. These symptoms signal that the mass is affecting brain function or pressure dynamics, demanding immediate attention.
Steps for Diagnosis and Medical Evaluation
If a lump on the head is growing, changing, or consistently causing pain, consulting a healthcare provider, such as a primary care physician or a dermatologist, is the next step. The initial evaluation involves a physical examination of the lump, assessing its size, consistency, mobility, and any signs of infection or inflammation. The doctor will also conduct a neurological assessment to check for red-flag symptoms associated with internal pressure or brain involvement.
Management for symptomatic external cysts is typically straightforward and may involve a simple in-office procedure. This includes draining the cyst to relieve pressure or surgical excision to remove the entire cyst wall and prevent recurrence. If the physical exam suggests a deeper problem, the doctor will order diagnostic imaging, usually a Computed Tomography (CT) scan or Magnetic Resonance Imaging (MRI). An MRI is useful as it can differentiate between a fluid-filled cyst and other solid masses, determining if the source of the headache is external or internal.