Osteochondroma is a common benign (non – cancerous) bone tumor in kids. It develops near the growth plate of long bones (thigh, shin, and upper arm) usually as a child is going through a growth spurt. When a child stops growing the tumor stops growing too. 1

Osteochondroma can be a single tumor (solitary osteochondroma) or a more aggressive type that is due to a hereditary condition, multiple ostoechondromatosis. Multiple osteochondromatosis can cause abnormal growth of bones like bowed legs, knock-knees, or short stature. There is a very small risk (1%) that a solitary lesion will become malignant, and a 10% chance that multiple osteochondromatosis will become malignant. 2  If these do transition to a malignant tumor they become chondrosarcomas because they are tumors that are made up of cartilage cells.

Cause of Osteochondroma

There is no known cause of solitary (single lesion) osteochondroma. Multiple osteochondromatosis is an inherited condition meaning at least one of the child’s parents had the disease. There has been research showing that a mutation in two genes is associated with development of both types of osteochondroma.3

Symptoms of Osteochondroma

Solitary osteochondromas don’t usually cause pain unless they are irritating soft tissues such as tendons or ligaments. They may cause numbness or tingling if they are irritating a nerve, or cause a change in blood flow if they are near a blood vessel. Usually they are found when a child has an x-ray for an unrelated injury (an incidental finding).

Diagnosis of Osteochondroma

X-ray, typically for an unrelated reason, is usually the first test that shows an osteochondroma. The tumor may appear as a flat outgrowth near the growth plate, or it may appear to have a ‘stalk’ attaching it to the bone near the growth plate.

A CT scan or MRI may be requested in order to see the extent of the lesion and if it is pressing on other structures.

A biopsy may be done to rule out a cancerous process.

Treatment of Osteochondroma

Osteochondromas stop growing when a child has stopped growing so it’s highly likely that nothing will need to be done. It’s o.k. to just watch the tumor if it’s not pressing on a nerve or blood vessel, or in an area that effects the child’s function. Medications may be prescribed if a child is having some pain. If the tumor is painful or causing problems by irritating other structures like nerves, tendons or blood vessels, it can be surgically removed (excised).

It’s important to follow-up with a physician on a regular basis to monitor any growth of the tumor or if there are significant changes in symptoms.

1. Reijnders, Christianne; Liesbeth Hameetman; Judith VMG Bovée (September 2008). "Bone: Osteochondroma". Atlas of Genetics and Cytogenetics in Oncology and Haematologyde.
2. Andrea, CE; Reijnders CM; Kroon HM; De Jong D; Hogendoorn PC; Szuhai K; Bovée JV (1 March 2012). "Secondary peripheral chondrosarcoma evolving from osteochondroma as a result of outgrowth of cells with functional EXT". Oncogene 31 (9): 1095–1104.
3. Zhang, F; Liang J, Guo X, Zhang Y, Wen Y, Li Q, Zhang Z, Ma W, Dai L, Liu X, Yang L, Wang J. (29 August 2013). "Exome sequencing and functional analysis identifies a novel mutation in EXT1 gene that causes multiple osteochondromas.". PLOS ONE 8 (8).