Bone tumours grow when cells in the bone divide without control, forming a mass of tissue. While most bone tumours are benign and do not spread to other areas of the body it may still weaken bones and lead to broken bones or cause other problems.
Bone cancer destroys normal bone tissue. It may start in the bone or spread from other parts of the body (called metastasis). Osteoma is a type of bone cancer that usually affects the skull and legs in children and young adults usually below the age of 20 however, it can be found in other parts of the body. It is seldom seen in older ages.
An osteoma involves growth of a new piece of bone growing on another piece of bone. It is a benign tumour. When the bone tumour grows on other bone it is known as “homoplastic osteoma”; when it grows on other tissue it is called “heteroplastic osteoma”. Osteoma can be broadly classified into two types:
- Compact osteomas: These are composed of mature lamellar bone
- Spongy osteomas: These are composed of trabecular bone with marrow
The cause of osteomata is uncertain, but commonly accepted theories propose embryologic, traumatic, or infectious causes. Osteomata are also found in Gardner’s syndrome. Larger craniofacial osteomata may cause facial pain, headache, and infection due to obstructed nasofrontal ducts. Often, craniofacial osteoma presents itself through ocular signs and symptoms.
- The most common symptom of Osteoma is pain which can be relieved with over the counter (OTC) pain medication in the early stages. After the benign tumour develops further, the pain cannot be alleviated with OTC medication. At this stage, we often see swellings. In some cases however, the pain level remains the same for years, and the doctor may prescribe specific medications to keep the pain at bay. The tumour is often found through x-ray imaging. Characterized by being less than 1.5 cm in diameter, osteoid osteomas most frequently occur in young men and could occur in any bone of the body.
Severe pain typically occurs at night, but can also be constant at any time of day. The primary complaint may only be of dull pain which is non radiating and persistent but increases significantly at night which can be handled with prescribed medication from the doctor. Apart from this the other symptoms are:
- Dull pain that escalates to severe at night OR slight pain, rising to become severe even at night time, affecting sleep quality
- Muscle atrophy
- Bowing deformity
- Increased or decreased bone growth
The exact cause for osteoid osteoma is unknown, however, they are caused by an excess of osteoblasts. Osteoblasts are cells in our bodies responsible for building new bone. The excessive bone associated with osteoid osteoma is made up of osteoid bone a different type of bone that we do not normally see proliferating in excess. Osteoid osteoma also secrete prostaglandins, a chemical signalling molecule in our bodies that is often associated with producing pain. A few other conditions are also associated with osteoid osteoma:
- Osteomyelitis: This is an infection of the bone that is easily differentiated from osteoid osteoma with imaging.
- Stress fractures: Unlike osteoid osteoma, the pain of a stress fracture usually worsens with activity.
- Osteoblastoma: An osteoblastoma is another noncancerous, bone-forming tumour, but it is more commonly found in the spine, is generally larger than 2 centimetres, and the pain does not usually improve with aspirin. These symptoms easily differentiate them from osteoid osteomas.
Osteoid osteoma can be diagnosed with:
- X-rays: Most osteoid osteomas are diagnosed with X-rays, in which the tumour usually appears as a small area of thickened bone around a central core.
- CT scans or MRIs: About 25 percent of osteoid osteomas are not visible on X-rays because thickened bone has obscured the picture, and thus will require these further imaging methods CT scans and/or MRIs.
- Biopsy: A biopsy is a small sample of the bone that is usually extracted with a needle. These are rarely needed to confirm the diagnosis of osteoid osteoma.
Osteoma may resolve spontaneously in approximately 33 months, the reason for which is unknown. However, the tumour and the pain it causes has reportedly lasted consistently for 9 years in a rare case, until the tumour was finally discovered and removed, curing the patient. So it’s possible it might never resolve by itself.
The type of treatment may also vary based on the health of the individual with the tumour. If an individual is healthy and is willing to endure the pain, pain relievers are given until the tumour resolves, unless the pain keeps the patient awake during the nights. If the patient does not want to endure the pain or to be treated with non-steroidal anti-inflammatories, surgical or percutaneous ablation may be considered. If surgery is preferred, the individual may be referred to an orthopaedic surgeon to perform the ablation. Post-surgery therapy and strengthening may be needed, depending on the tumour location and health of the individual.
Presently, percutaneous radiofrequency ablation is the preferred treatment option. It is a minimally invasive procedure in which radio frequencies are passed beneath the skin through a needle to kill the tumour cells by heating them to a high temperature. It is performed by a radiologist and is preferred because it is done under general anaesthesia and does not weaken the bone as much as surgery does. The recovery time is also shorter for this treatment.
While pain may be relieved through medication, ablation may have to be performed in some more serious cases.