A lump appearing suddenly or gradually near the collarbone (clavicle) can be unsettling due to the bone’s prominence beneath the skin. The clavicle is a long, thin bone connecting the shoulder blade to the breastbone, linking the arm to the body. Its location makes it a reference point for many underlying structures, including major blood vessels, nerves, and lymph nodes. Because abnormalities in the bone or surrounding soft tissues are easily felt, a new lump demands attention. While this article explores possible causes, it is not a substitute for a professional medical diagnosis, which is necessary for any new or concerning lump.
Causes Related to Acute Trauma and Mechanical Stress
Lumps that appear immediately following a physical event often relate to acute trauma or mechanical disruption of the joint structure. A clavicle fracture, commonly caused by a fall onto the shoulder or an outstretched arm, frequently results in a hard lump. When the bone breaks, displaced fragments can create a noticeable deformity and cause sharp pain that worsens with arm movement. Even after healing, the body’s repair process creates a bone callus, which can leave a persistent, hard lump at the fracture site.
The joints connecting the clavicle can also be disrupted, leading to a lump. A separation of the acromioclavicular (AC) joint occurs when supporting ligaments tear, causing the end of the collarbone to protrude upward near the shoulder joint. If trauma did not involve a bone break or joint separation, the lump might be a hematoma. A hematoma is a localized collection of clotted blood beneath the skin, forming after an impact damages underlying blood vessels. This tender, swollen area usually resolves as the body reabsorbs the blood.
Swollen Lymph Nodes and Inflammatory Responses
Lumps in the collarbone area frequently originate from the immune system, specifically the supraclavicular lymph nodes located just above the clavicle. These nodes are part of the lymphatic system, acting as filters that collect fluid draining from the head, neck, chest, and arms. When the body is fighting an infection, these nodes swell as they fill with immune cells, resulting in a tender, movable lump.
Infections such as an upper respiratory illness, strep throat, or a skin infection in the arm can trigger this temporary swelling (lymphadenopathy). Typically, this swelling resolves once the underlying infection clears. Inflammatory conditions can also cause swelling in the surrounding tissues, such as bursitis, which is the inflammation of fluid-filled sacs near the joints. A localized pocket of infection called an abscess can also develop, presenting as a painful, warm, and soft lump that may require drainage.
The specific location of the swollen lymph node can provide diagnostic clues. Swelling in the right supraclavicular node usually relates to the chest or lungs. Conversely, swelling on the left side drains the thoracic duct and areas like the abdomen and pelvis, sometimes indicating a distant issue. Persistent lymph node swelling, even when painless, warrants medical attention, as it can signal a widespread inflammatory process or a serious condition.
Non-Traumatic Tissue Growths
Some lumps develop slowly over time and are masses of tissue unrelated to recent injury or acute infection. The most common benign growths are lipomas, which are soft, slow-growing tumors composed of fat cells that form between the skin and muscle. These growths are typically painless and highly mobile, shifting easily when pressed.
Another common non-traumatic lump is a cyst, an encapsulated sac filled with fluid, keratin, or other material. Cysts often feel firmer and more fixed than lipomas and can become painful or inflamed if they rupture or become infected. Less commonly, a lump can be a benign bone growth, such as an osteochondroma, or a localized bone infection called osteomyelitis. Osteomyelitis causes swelling, localized pain, and fever, requiring prompt treatment with antibiotics.
A pulsating lump near the collarbone suggests vascular issues, such as an aneurysm or compression of an artery beneath the clavicle. This presentation may be a symptom of a vascular form of thoracic outlet syndrome, where structures passing through the space between the collarbone and the first rib are compressed. In rare instances, a persistent, hard, or fixed lump, particularly in the supraclavicular area, can signal malignancy. Enlargement of these nodes can indicate lymphoma or a cancer that has spread from another location, such as the lung or breast. The characteristics of these growths, such as their texture, mobility, and growth rate, are important diagnostic factors requiring a thorough physical examination.
Signs Indicating Immediate Medical Review
While many collarbone lumps are benign, certain signs indicate the need for prompt evaluation by a physician. Any lump that is growing rapidly in size should be examined immediately. Lumps that are hard, fixed to the underlying tissue, and non-tender are particularly concerning and require urgent investigation. This fixed quality suggests the mass may be tethered to deeper structures rather than being a mobile, superficial growth.
Other systemic signs accompanying a lump are considered red flags. These include unexplained weight loss, night sweats, or a persistent fever. Immediate medical attention is necessary if the lump is accompanied by significant pain, redness, or warmth, or if there is numbness or coldness in the arm or hand. A physician will typically perform a physical examination and may order diagnostic tests, such as an X-ray, ultrasound, or CT scan, to visualize the tissue and determine the lump’s origin. In some cases, a biopsy may be needed to collect a tissue sample for definitive diagnosis.