A lump discovered in the occipital region, or the back of the head, can cause concern. Most lumps found on the scalp are harmless, often representing common skin conditions or minor injuries. These masses occur in the skin, soft tissue, or bone. Their characteristics—such as texture, mobility, and tenderness—often suggest their origin. This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
Causes Originating in the Skin and Soft Tissue
Lumps on the back of the head often arise from structures within the skin layers or the fatty tissue beneath it. A common type is a lipoma, a benign tumor composed of fatty tissue. Lipomas typically feel soft and rubbery, are easily movable beneath the skin, and grow slowly. They usually do not cause pain unless they compress a nerve.
Another frequent occurrence is an epidermoid cyst, which forms when surface skin cells become trapped and accumulate keratin. These cysts are firm, slow-growing nodules sometimes identified by a small, dark pore, or punctum, on the surface. If an epidermoid cyst ruptures or becomes infected, it may become red, tender, and discharge a thick, foul-smelling material.
Deeper growths within the scalp’s hair follicles include pilar tumors, also known as trichilemmal cysts. These are usually firm, smooth, and dome-shaped nodules that develop from the outer root sheath of the hair follicle. Folliculitis, or inflammation of the hair follicles, presents as red, sometimes pus-filled bumps that resemble acne. These bumps can be sore and often resolve once the underlying infection or irritation clears.
Causes Related to Trauma and Lymph Node Activity
Some lumps in the back of the head are temporary reactions to an external event, such as infection or injury. The occipital lymph nodes, located at the base of the skull, are part of the immune system and filter fluid from the scalp and neck. When an infection is present (e.g., ringworm, impetigo, or a common cold), these nodes can swell, a condition known as lymphadenopathy.
Swollen occipital lymph nodes often feel tender and may be palpable on one or both sides of the head. This swelling indicates the body is fighting an infection in the area they drain. The nodes usually return to their normal size once the underlying illness is resolved. They can also swell due to systemic conditions like autoimmune diseases or certain viral infections.
A hematoma is a common reactive lump, which is a collection of blood under the skin forming after blunt trauma to the head. This bump, often called a goose egg, is typically soft and swollen immediately following the injury. It gradually resolves as the body reabsorbs the pooled blood. While most scalp hematomas are minor, a severe blow can cause a subdural or epidural hematoma, which involves bleeding near the brain and requires immediate medical attention.
Structural and Bony Growths
Lumps that feel hard and immovable are often related to the underlying bone structure of the skull. Osteomas are benign bone tumors that grow slowly and consist of dense bone tissue. These growths are typically rock-hard, non-tender, and fixed to the skull, as they are extensions of the bone itself.
While osteomas are generally rare in the occipital bone, they are usually asymptomatic. They may only be noticed if they reach a size that causes cosmetic concern or, rarely, pain. The fixed nature of an osteoma is a distinguishing feature compared to the mobility of a lipoma or a lymph node. Proliferating pilar tumors, though originating in soft tissue, can become large and firm, sometimes mimicking bone density due to extensive keratin and calcification.
Warning Signs and Next Steps
Recognizing specific symptoms determines when a lump requires professional medical evaluation. Lumps that exhibit rapid growth, are fixed and hard, or are accompanied by systemic symptoms should be checked by a healthcare provider. Systemic red flags include unexplained weight loss, persistent fever, or night sweats.
Local signs of concern include extreme pain, skin changes (such as color change or ulceration), or the lump returning after removal. Any lump that causes neurological symptoms warrants prompt medical assessment. These symptoms include blurred vision, chronic headache, confusion, or weakness on one side of the body. They can suggest pressure on the brain or a more serious underlying condition.
Diagnosis typically begins with a physical examination, where a healthcare professional assesses the lump’s size, texture, and mobility. If the cause is unclear, imaging studies like an ultrasound, CT scan, or MRI may be ordered to visualize the internal structure of the mass. In some cases, a biopsy may be necessary. This involves taking a small tissue sample to examine the cells under a microscope and confirm the lump’s definitive nature.