Finding an unexpected lump on your body, especially in a central location like the chest, can understandably cause concern. The sternum, or breastbone, is the long, flat bone situated in the center of the chest, connecting the ribs via cartilage. A lump in this area can originate from the skin, the soft tissues surrounding the bone, the cartilage, or the bone structure itself. This article explores common explanations for a sternal lump. This information provides general context only and is not a substitute for a professional medical diagnosis.
Soft Tissue and Inflammatory Causes
Many sternal lumps originate in the layers of skin and fat, or from the inflammation of the nearby cartilage. These soft tissue causes are often benign and represent the most common reasons for finding a lump near the breastbone. Lumps arising from the skin include fatty deposits called lipomas. Lipomas are non-cancerous, typically slow-growing, soft, movable under the skin, and may feel doughy to the touch.
Another surface-level cause is a sebaceous cyst, also known as an epidermal inclusion cyst, which forms when a skin gland duct becomes blocked. These cysts are sacs beneath the skin filled with keratin and cellular debris, presenting as a smooth, round, and movable lump. While generally harmless, these cysts can become inflamed, tender, or infected, requiring medical attention.
Deeper, non-bony lumps often involve the costochondral junctions, the cartilage connecting the ribs to the sternum. Costochondritis is an inflammation of this cartilage, causing chest wall pain that can be mistaken for a heart issue. This condition usually presents without visible swelling but causes painful, localized tenderness when pressed.
Tietze syndrome is a similar inflammatory condition distinguished by the presence of noticeable, non-pitting swelling over the affected joint, often the second or third rib cartilage. This swelling can feel like a firm lump. It is typically accompanied by localized pain that increases with deep breathing or movement.
Structural and Bony Manifestations
Lumps that feel hard and fixed often arise directly from the sternum bone or its surrounding cartilage structures. These structural lumps differ from the soft, movable masses of the skin and fat. One manifestation is an osteochondroma, a benign bone tumor that appears as a cartilage-capped bony outgrowth. Osteochondromas can occur in the chest wall, presenting as a hard, fixed, and typically painless mass.
Sternum anomalies can also be perceived as a fixed lump on the breastbone. An old, healed fracture can result in a bony callus, which is the body’s natural repair tissue that feels like a solid lump. The xiphoid process, the small piece of cartilage at the bottom of the sternum, can also become inflamed or damaged. This leads to swelling and a palpable lump in the lower chest region, a condition known as xiphoid syndrome, which often follows trauma or repetitive strain.
Fibrous dysplasia is a rare, non-cancerous condition involving the replacement of normal bone tissue with abnormal fibrous connective tissue. When this occurs in the sternum, it can cause the bone to swell and present as a hard, firm lump. This skeletal developmental anomaly requires medical evaluation to confirm the diagnosis and rule out other bone lesions.
When to Seek Immediate Medical Attention
While many sternal lumps are benign, certain characteristics indicate a need for prompt medical evaluation. A lump should be professionally assessed if it exhibits any of the following “red flags”:
- It is rapidly increasing in size over a short period (weeks or months).
- It feels hard, fixed, and immovable to the surrounding tissues.
- It causes severe and persistent pain that does not improve with rest or over-the-counter medication.
- Systemic symptoms are present, such as unexplained weight loss.
- The patient experiences persistent fever or drenching night sweats.
A physician will typically begin the diagnostic process with a thorough physical examination and a detailed medical history. If the lump’s nature is unclear, imaging tests such as an X-ray, ultrasound, or CT scan may be ordered to visualize the internal structure. If malignancy or infection is suspected, a definitive diagnosis often requires a biopsy, where a tissue sample is taken and examined in a laboratory. Though rare, sternal masses can sometimes be a sign of infection, such as osteomyelitis, or a primary bone tumor like a sarcoma.