Possible causes of a cump on the rib cage that feels like bone
A hard lump on the rib cage, which may feel like bone to the touch, can be caused by multiple conditions. These can range from abnormal bone growth, through complications of bacterials infection to cancer.
Congenital (birth) anomalies
Supernumerary intrathoracic rib is a rare congenital (present from birth) anomaly, which presents as an extra rib or bone growth growing on or in the rib cage. This is quite rare, and is usually an incidental finding on a chest X-ray, as it doesn't cause symtpoms. Sometimes, this can be positioned in a way so that it can be felt through the skin.
Another condition like this is a cervical rib, which involves growth or a rib-like structure out of the cervical spine, where it meets the rib cage. This usually presents as a hard lump at the intersection of the neck and chest [1].
Post-traumatic bone lesions
A post-traumatic fibro-osseous lesion is a rare type of bone growth which occurs when the body over-reacts in healing a bone injury following trauma. This is more common on the lower ribs. As this is essentially extra bone, this presents as a lump which feels hard to the touch [2].
Tuberculosis
In rare cases, a lump on the rib cage could be a consequence of tuberculosis infection involving the ribs. This creates a mass that resembles bone metastasis of tumours on a chest X-ray, however sometimes can be felt through the skin as a mass as well [3].
Tumours and cancers
There are multiple types of cancer which can present as a lump on the rib cage that feels like bone:
- Giant cell tumour - this usually grows on long bones, however can manifest in the rib [4];
- Aneurysmal bone cyst - a type of lesion where a blood-filled cyst forms inside the bone. This can progress to cancer, and can occur in the rib, presenting as a lump [5];
- Chondroblastoma - a rare, benign tumour that originates from cartilage. Cartilage connects the rib bones to the spine and the sternum, therefore chondroblastomas there can be palpable and feel hard;
- Osteosarcoma - this is a tumour that forms from the bone cells. While they usually form on long bones in young adults as a consequence of rapid growth, they can form on the ribcage as well.
- Ewing's sarcoma - another type of bone tumour. This type of sarcoma is very malignant and aggressive, however also very rare.
- Lung cancer and metastases - In rare cases, lung cancer can invade bone, with the ribs being an easy target due to their close proximity. Overall, 2.3% of lung cancers invade skeletal muscles. This is particularly common with squamous cell carcinomas.
Diagnosing a bone-like lump on the rib cage
The diagnostic process for a lump on the rib cage that feels like bone involves several steps.
- Physical examination - the doctor evaluates the shape, size and appearance of the lump. Furthermore, history of associated symptoms such as pain, coughing, or recent traumas is collected. It is important to note that a detailed history is essential in the diagnostic process [6].
- Imaging - techniques including X-ray and/or CT scan, or magnetic resonance (MRI) are used to provide more insight into the shape, size and location of the mass, as well as establish the presence of inflammation around the lesion [6, 7]. Additionally, imaging is important to establish the surrounding anatomy when planning a surgery. In some cases, a radioactively-labelled chemical may be used to determine the metabolic activity of the tumour and help stage the cancer.
- Biopsy - removing a small sample of tissue from the lump for examination under a microscope, where the tissue is stained with specialised dyes that allow for expression of certain molecules [8, 9].
Treatment of a lump on the rib cage
The exact treatment approach is usually tailored to the specific diagnosis and the patient's therapeutic objectives.
For example, if the lump is a benign lesion that doesn't cause issues, nothing needs to be done except for monitoring of symptoms or for growth of the lesion.
If a lump causes inconvenience such as pain, it is usually removed surgically. The exact approach of the surgery depends on the location and nature of the lump, as well as the surrounding anatomy.
If the lump is cancerous, removal is the primary course of action. The goal of this is to remove all of the tumour. Sometimes, a portion of the healthy bone is also removed to ensure that all cancerous and/or potentially cancerous cells are removed to minimise the chance of recurrence and/or metastasis [5].
Following surgery, reconstruction of the bone is performed if a large portion of the bone has to be removed. This can be done with supporting materials such as mesh or gore-tex [10].
In addition to surgery, a decision can be made to deploy radiotherapy to the tumour site, either as a safety to kill all potentially cancerous cells left behind, or, if surgery is not possible (for example due to surrounding anatomy) to shrink the tumour.
Some targeted therapies and immune therapies are available and/or investigated in clinical trials. However, in some cases, especially in high-grading cancers that metastasise, systemic cytotoxic chemotherapy is administered [11].
Summary
A lump on the rib cage that feels like bone can be a consequence of abnormal bone growth and therefore should not cause any issues. However, in some cases, this can be more serious, either as a consequence of tuberculosis, or cancer.