An enchondroma is a common non-cancerous tumour made up of specialized cells called chondrocytes. Enchondromas are usually found in the bones of the hands or feet, but they may occur in almost any bone in the body. They usually affect young and middle-aged adults. In most cases, enchondromas do not cause symptoms and are often found when imaging (such as an X-ray or CT scan) is performed for another reason. When they do cause symptoms, pain or enlargement of the affected area is most common.
Cartilage is a special elastic type of tissue, which means that it can be bent or compressed (put under pressure) without breaking, a bit like rubber. Cartilage is found throughout the body, although most cartilage is found between bones where it helps form a cushion that protects the ends of the bones from damage. Some parts of the body, such as the nose and ears, are made almost entirely out of cartilage. Cartilage is made up of cells called chondrocytes, surrounded by specialised tissue called a matrix that gives it its rubbery nature.
The diagnosis can be made after a small tissue sample is removed in a procedure called a biopsy or when the entire tumour is removed in a procedure called a resection or curettage. In some cases, the diagnosis can be made without a tissue examination because the appearance on imaging is unique. Because they are not cancerous and many grow either very slowly or not at all, some patients may choose, along with their surgeons, not to have the tumour removed.
Under the microscope, an enchondroma is made up of chondrocytes and matrix that look very similar to normal cartilage. At the edge of the tumour, there is a clear border between the tumour and the surrounding normal bone tissue. This feature is important because a type of bone cancer called chondrosarcoma can look similar to an enchondroma under the microscope.
In contrast to an enchondroma, the border between a chondrosarcoma and the normal bone is less clear as the tumour cells in a chondrosarcoma spread into and destroy surrounding bone. This spread into normal bone can also be seen when imaging such as an X-ray is performed. For this reason, your pathologist may also look at your X-ray or other imaging results to make sure there is no bone destruction before making the diagnosis of enchondroma.