Finding a lump in the submandibular or upper neck region can cause worry, as this area houses many different tissues and glands. The space beneath the jaw contains muscles, fat, blood vessels, major salivary glands, and a network of lymph nodes, all of which can swell or form masses. Since the characteristics of a lump—such as its size, texture, mobility, and tenderness—are determined by its origin, a definitive diagnosis requires a professional medical evaluation. Understanding the potential causes can provide context for this common physical finding.
Lumps Caused by Infection and Immune Response
The most frequent cause of a lump under the jaw is the temporary enlargement of lymph nodes. These small, bean-shaped structures function as filtering stations for the immune system, trapping and destroying pathogens like bacteria and viruses. When the body detects an infection in the mouth, throat, or upper respiratory tract, these nodes rapidly swell as immune cells multiply to fight the invaders.
Swollen lymph nodes, medically termed lymphadenopathy, often present as soft, tender, and movable lumps beneath the jawline. Common viral infections, such as the cold, flu, or infectious mononucleosis, can trigger this localized response. Bacterial infections, including strep throat or an infection from a dental abscess, are also frequent culprits. The nodes typically become painful to the touch and may feel warm due to the inflammatory process.
This swelling is a normal, temporary reaction indicating the immune system is resolving the underlying illness. Once the infection clears, the lymph nodes typically return to their normal size within days or a few weeks. If the node itself becomes infected, a condition called lymphadenitis, it can become more painful and may require specific treatment.
Benign Growths and Subcutaneous Tissue Lumps
Lumps can also arise from the soft tissues and skin layers beneath the jaw, often being structural rather than a response to infection. Lipomas are common non-inflammatory lumps, consisting of a collection of mature fat cells that form a benign tumor. These masses feel soft, doughy, and are easily movable, often growing slowly over months or years. A lipoma is generally painless unless it presses against a nearby nerve.
Another frequent finding is the epidermoid cyst, which forms when surface skin cells move inward and multiply in the dermis. These cells secrete keratin, a protein that creates a thick material filling the cyst sac. Unlike a lipoma, an epidermoid cyst often feels firmer and is less mobile because its sac is fixed within the skin layers. If the cyst ruptures beneath the skin, it can cause a sudden, painful inflammatory reaction that may mimic an infection.
Benign growths like fibromas, tumors composed of fibrous connective tissue, may also occur. These masses are typically firm and slow-growing. While these non-glandular lumps are almost always harmless, removal may be recommended if they become cosmetically bothersome or interfere with function. These lumps are defined by their chronic presence and lack of tenderness or pain.
Issues Related to Salivary Glands and Other Structures
The submandibular glands, one of the three major pairs of salivary glands, are located directly beneath the jaw and are a distinct source of lumps. These glands can swell due to inflammation or obstruction. Sialadenitis is a bacterial infection of the salivary gland, resulting in painful, firm swelling that may include fever and the drainage of pus into the mouth. This condition typically requires antibiotics and increased hydration.
Sialolithiasis involves the formation of calcified salivary stones (sialoliths) within the duct or the gland itself. Since the submandibular gland produces the majority of saliva, it is the most common site for these stones. A classic symptom of blockage is sudden, localized swelling and pain under the jaw that worsens during mealtimes. This occurs because eating stimulates saliva production, but the flow is blocked, causing the gland to rapidly expand.
Tumors can also originate from the salivary glands; about 80% of these are benign growths like pleomorphic adenomas. Salivary gland tumors typically present as a firm, slow-growing, and often painless lump. The lack of pain can allow these masses to grow larger before detection.
When to Seek Professional Medical Evaluation
While many lumps under the jaw are benign and temporary, certain characteristics require prompt medical attention. Any lump that persists for longer than two to four weeks without improvement should be evaluated by a healthcare provider, as persistence suggests a cause beyond a common acute infection.
Lumps exhibiting specific physical qualities are considered concerning “red flags.” These include a mass that feels hard, fixed, or immobile, meaning it does not move easily under the skin when pressed. Painless lumps can also be more worrisome than painful ones because malignancy often does not cause pain until advanced stages.
Other systemic symptoms accompanying the lump should prompt an immediate visit to a doctor or specialist, such as an otolaryngologist (ENT). These symptoms include:
- Unexplained weight loss
- Night sweats
- A persistent fever
- Change in the surrounding skin, like redness or ulceration
- Difficulty with swallowing or breathing
A medical professional can perform a physical examination, order imaging tests like an ultrasound, or recommend a biopsy to determine the lump’s exact nature.