A lump on the side of the neck often causes immediate concern, but the majority of these masses are harmless. The neck is a complex area containing many different structures, including glands, muscles, and vessels, all of which can develop a noticeable swelling. Because a neck lump can arise from various tissues and signal a wide range of conditions, from a simple infection to something more serious, a professional medical evaluation is always necessary. This information serves to educate on the possible origins of these lumps, but it is not a substitute for a diagnosis from a healthcare provider.
The Most Common Cause: Swollen Lymph Nodes
The most frequent reason for a lump on the side of the neck is an enlarged lymph node, medically known as lymphadenopathy. Lymph nodes are small, bean-shaped organs that function as filters within the lymphatic system, which is an integral part of the body’s immune defense. They contain specialized white blood cells that trap and destroy invading pathogens.
When the body is fighting an infection, the cells inside the nodes multiply rapidly, causing the node to swell and become palpable. This reactive lymphadenopathy is a normal immune response, and the swelling often appears suddenly and is temporary. Common localized infections that cause swelling in the neck nodes include the common cold, strep throat, ear infections, or a dental abscess.
Nodes that swell due to infection are typically soft or rubbery, mobile under the skin, and often tender or painful to the touch. They usually measure between 1 and 2 centimeters in size and will gradually reduce as the underlying infection resolves, which can take a few days to a few weeks. Generalized inflammation from conditions like infectious mononucleosis or certain autoimmune diseases can also cause nodes to enlarge across the neck.
Structural and Glandular Lumps
While lymph nodes are the most common cause, a lump on the neck can also originate from other structures, including glands, skin, and congenital remnants. These non-lymphatic masses tend to have different characteristics and locations. A key indicator for a thyroid nodule is its location in the lower, central part of the neck and its upward movement when swallowing.
Thyroid nodules are very common localized growths within the thyroid gland, and while most are benign, they require investigation. Swelling can also originate from the salivary glands, particularly the parotid gland near the ear or the submandibular gland under the jaw. These glands may swell due to a viral infection, like mumps, or from a blockage caused by a salivary duct stone.
Benign lumps originating from the skin or soft tissue are also frequent, such as lipomas and sebaceous cysts. A lipoma is a soft, slow-growing, fatty tumor that is typically painless and feels doughy to the touch. Sebaceous cysts form when a hair follicle or skin gland becomes blocked, creating a smooth, movable sac just beneath the skin. Less common are congenital cysts, like a branchial cleft cyst, which results from incomplete closure of embryonic structures.
Characteristics That Signal Concern
Although most neck lumps are benign, certain physical characteristics and associated symptoms elevate the concern for a more serious underlying condition. The consistency and mobility of the mass are important indicators during a physical examination. A lump that feels hard and unyielding, often described as “stony,” is considered more suspicious than a soft or rubbery one.
Masses that are fixed or tethered to the underlying tissue—meaning they do not move easily when pushed—raise a greater concern. Any lump that rapidly increases in size or persists for longer than three to four weeks should be medically evaluated, especially if it exceeds 1.5 centimeters in diameter. These features are particularly concerning in adults over the age of 40 and in individuals with a history of tobacco or heavy alcohol use.
Accompanying systemic symptoms also necessitate prompt investigation. These include unexplained weight loss, night sweats, or a persistent fever that does not resolve. Local symptoms like difficulty or pain when swallowing, persistent hoarseness or voice changes, or unilateral nasal symptoms should also prompt a medical appointment.
Seeking Medical Evaluation
Given the variety of potential causes, a healthcare provider must conduct a thorough evaluation to determine the nature of any persistent or concerning neck lump. The diagnostic process begins with a detailed medical history and a physical examination, assessing the lump’s size, consistency, and mobility. The provider will also consider the duration of the lump and any associated risk factors, such as smoking history.
If the mass does not resolve after observation or presents with concerning characteristics, further testing is typically required. The first line of investigation often involves an ultrasound scan, which uses sound waves to create a real-time image of the mass and surrounding structures. This imaging helps determine if the lump is solid, cystic (fluid-filled), or part of a gland.
If imaging reveals suspicious features, the next step is often a fine-needle aspiration (FNA) biopsy. This minimally invasive procedure uses a thin needle, often guided by ultrasound, to collect a small sample of cells for laboratory analysis. This cellular analysis can usually distinguish between a benign inflammatory process and a malignant one, providing the definitive diagnosis needed to guide treatment.