The chest cavity is surrounded by three different groups of bones: the rib cage, the sternum, and the clavicles. The sternum (also known as the breast bone) lies right in the middle of the front of the chest cavity. It is attached to the bones of the rib cage as well as the clavicles (also known as collar bones). The sternum, which can easily be felt by hand, is made up of three bones:
- the manubrium,
- the body, and
- the xiphoid process
The manubrium is the uppermost bone of the sternum and can be felt just below the neck. The body of the sternum lies below the manubrium and is the longest bone in the sternum. The bottom part of the sternum is made up of the xiphoid process, which is a small pointed bone attached to the body of the sternum.
Meaning of Sternal Swelling
Even though the bones of the sternum are flat, their surfaces are not smooth. The top of the sternum has notches for the attachment of the collar bones. There are facets on the sides of the sternum for attachment of the ribs. The body of the sternum also has many transverse ridges on its surface. The xiphoid process at the bottom of the sternum has a pointed end that faces downwards. Despite the presence of an uneven surface, the sternum looks and feels flat in normal conditions. In certain situations, one might be able to feel or see swollen lumps or regions over the sternum. These can be caused by an underlying disease and should be investigated by a doctor.
Other Breastbone Symptoms
Feeling or seeing some swollen masses on the sternum is usually the first cause for concern. If sternal swelling is accompanied by any of the following symptoms, then one must pay a visit to the doctor immediately for further investigations. Accompanying signs and symptoms may include:
- Pain and tenderness occurs in the area where the sternum lies.
- The area over the sternum looks reddish.
- The skin over the sternum feels warm upon touching.
- Breathing, especially inhaling, is painful.
Even when the above mentioned symptoms do not occur along with the sternal swelling, it is still a good idea to visit the doctor for a checkup in order to rule out any serious underlying cause.
Causes of Sternal Swelling
Sternal swelling or masses can result from a variety of causes:
- Injury and inflammation: Even though one can easily feel the sternum bone by touching the overlying skin, there are layers of subcutaneous connective tissues that separate the two. Muscles that connect to the sternum and the ribs also contribute to the tissue layer above the sternum through their tendons. Injuries to either the sternum bone or the overlying connective tissues can cause swelling in the sternal region.
- Fractures of the sternum bone (e.g, in motor vehicle and other high-impact accidents) can cause a swelling to appear over the fracture site due to inflammation of the overlying connective tissues. This swelling usually does not go away on its own and is accompanied by many of the symptoms described earlier.
In contrast, swelling that occurs without any sternal fractures can be due to inflammation of the overlying and surrounding tissues. For example, costochondritis is an inflammation of the cartilages through which the bones in the rib cage attach to the sternum. Similarly, lymphadenitis could involve inflammation of the lymph nodes near the sternum. In many cases, sternal swelling flares up quickly but subsides on its own. In some cases, sternal swelling might be mild enough to be unnoticeable.
- Infections: Certain infections of the sternal bone and the nearby glands and connective tissues also cause swelling over the sternum. An example of infection that affects the sternum bone is sternal osteomylitis. This inflammatory condition is caused by an infection that can either arise in the sternum (e.g., after an injury to the sternum bone) or spread to the sternum from other regions of the chest cavity.
In some cases, inflammation and swelling of the sternum could actually be a result of infections spread through the bloodstream from distant sites in the body. Mumps is an example of an infection of the salivary glands that also causes sternal swelling. Another example of a non-sternal infection causing sternal swelling is cellulitis, which affects the connective tissues that lie over the sternum.
- Cancer: Cancers of the bone and the blood can also cause sternal swelling. Examples of bone cancers that can affect the sternum are multiple myeloma and osteosarcoma. Lymphoma and leukemia are cancers of the lymphocytes (white blood cells) and bone marrow cells, respectively. These can also result in sternal swelling.
- Nutritional deficiency diseases: Deficiency of nutrients that play a key role in bone formation and maintenance can also result in abnormal sternal swelling. Two classic examples include vitamin C and vitamin D deficiency.
Rickets (in children) and osteomalacia (in adults) are bone deforming diseases caused by vitamin D deficiency. Vitamin D is an essential nutrient that supports bone mineralization. In the absence of vitamin D, bones become weak and soft. These conditions can result in a beaded appearance of the sternum.
Vitamin C is an essential nutrient that plays a central role in maintaining healthy connective tissues. In the absence of vitamin C, the connective tissues become weak and break down. In the sternal region, this can result in a beaded appearance over the sites where the ribs attach to the sternum.
- Paget’s disease: Paget’s disease is characterized by a repetitive cycle of abnormal bone destruction and re-growth, which leads to bone deformities. The exact cause of this disorder is not known, although both genetic factors and viral pathogens are suspected. Paget’s disease may affect bones only in certain regions of the body, although it can also lead to bone deformities throughout the body. Sternal swelling may or may not occur in Paget’s disease.
Treatment for Sternal Swelling
Sternal swelling may subside on its own if it is caused by an inflammation that resolves itself quickly. However, it could also be due to a more serious and sinister causative factor. The exact line of treatment depends on the cause of the sternal swelling, which should be determined by a doctor. A common tendency is to massage the are but this can sometimes worsen the causative condition.