A chondroma is a rare, slow-growing tumor made of cartilage that forms on or inside bones, or occasionally in nearby soft tissue. It is not cancer. Most chondromas cause no symptoms at all and are discovered by accident when imaging is done for an unrelated reason. They can occur in both children and adults, though they’re most often found in people between their teens and forties.
Where Chondromas Develop
The hands are the single most common location. Chondromas are actually the most frequent primary bone tumor of the hand, with the proximal phalanges (the finger bones closest to your palm) being the classic spot. Other common hand sites include the middle phalanges, metacarpals, and distal phalanges. The feet are another frequent location.
Beyond the hands and feet, chondromas can develop in the thighbone (femur) and upper arm bone (humerus). Less commonly, they show up in the ribs, pelvis, spine, collarbone, skull, or nasal sinuses. When a chondroma grows inside a bone, it’s called an enchondroma. When it develops in the soft tissue surrounding joints or tendons rather than in bone itself, it’s called a soft tissue chondroma.
Types of Chondromas
Enchondromas
These are the most common type. They grow within the central portion of a bone, typically near the end of a long bone in a region called the metaphysis. They tend to favor the ulnar (pinky) side of the hand bones. Most enchondromas are solitary, meaning only one develops.
Soft Tissue Chondromas
These are rarer. They arise from the tissue surrounding tendons, joints, or the spaces near joints rather than from bone itself. They affect men and women equally, typically appear between ages 30 and 60, and present as a slowly growing lump, most often in the hands or feet. Repeated minor trauma may play a role in triggering them. Importantly, they are not attached to the underlying bone, which helps distinguish them on imaging.
What Symptoms Feel Like
Most chondromas produce no symptoms whatsoever. When they do cause problems, the signs are typically mild: a dull ache in the area, subtle swelling, or a palpable lump if the tumor is close to the surface. In some cases, a chondroma weakens the surrounding bone enough that a minor bump or twist causes a fracture through the tumor site. This is called a pathologic fracture, and it may be the first indication that a chondroma exists. The bone breaks more easily than it should, prompting imaging that reveals the underlying tumor.
How Chondromas Are Found on Imaging
Because chondromas are often silent, many are discovered incidentally on an X-ray or CT scan ordered for something else entirely. On imaging, they have several recognizable features. X-rays typically show a well-defined area inside the bone with characteristic calcification patterns: small punctate (dot-like) or ring-shaped calcium deposits within the cartilage. CT scans can reveal these calcifications in greater detail, sometimes appearing as strip-like, sheet-like, or irregular patterns.
MRI is useful for getting a clearer picture of the tumor’s borders, its relationship to the surrounding bone cortex, and whether there are any features that raise concern for something more aggressive. A classic benign chondroma has smooth, well-defined margins, preserves the outer shell of the bone, and shows no signs of soft tissue invasion.
Telling a Chondroma From a Cancerous Tumor
The most important clinical question with any cartilage tumor is whether it’s truly benign or potentially a chondrosarcoma, which is a malignant cartilage tumor. This distinction can be genuinely difficult, especially in long bones like the femur, where the imaging overlap between a harmless enchondroma and a low-grade chondrosarcoma is significant.
Several imaging features point toward a more aggressive process: a moth-eaten or ragged pattern of bone destruction, loss of the normal fatty marrow trapped within the tumor, destruction of the outer bone cortex, soft tissue extending beyond the bone, and swelling in the tissue around the tumor. Cortical destruction and soft tissue masses are particularly telling, with 100% specificity for an aggressive process. High-grade malignant tumors may also show hemorrhagic necrosis and extension into a nearby joint. By contrast, a well-contained lesion with typical calcification and intact bone cortex is reassuring.
Treatment and Monitoring
Many chondromas require no treatment at all. If the tumor is small, painless, and clearly benign on imaging, your doctor will likely recommend periodic monitoring with follow-up X-rays or MRI to confirm it isn’t growing or changing character. This watchful approach is common and safe because these tumors grow very slowly.
Surgery becomes an option when a chondroma causes pain, leads to a fracture, or when imaging can’t reliably rule out a low-grade malignancy. The standard surgical approach is curettage: the tumor is scraped out of the bone cavity, and the space is filled with a bone graft or bone cement to restore structural strength. This is a relatively straightforward procedure with good outcomes, and it preserves far more function than removing a section of bone entirely.
Overtreatment is a recognized issue. Because it can be hard to distinguish a benign enchondroma from a very low-grade cartilaginous tumor on imaging alone, some lesions end up being surgically removed when monitoring would have been perfectly adequate. Research following patients with residual tumor tissue left after curettage has shown that even those small remnants can remain stable for years, causing no pain and showing no growth over average follow-up periods of nearly eight years. This supports a conservative, observation-first approach for tumors that aren’t causing active problems.
Conditions Involving Multiple Chondromas
Most people develop a single chondroma. In rare cases, however, multiple enchondromas appear throughout the skeleton. Two named conditions describe this pattern.
Ollier disease involves multiple enchondromas, often concentrated on one side of the body, that can cause bone deformities and unequal limb length, particularly when they develop during childhood growth. Maffucci syndrome combines multiple enchondromas with vascular abnormalities (tangles of blood vessels) in the soft tissue. Both conditions occur sporadically, with no family history. No inherited genetic mutations have been identified, but tumor tissue from about 80% of affected individuals carries specific mutations that are present only in the tumors themselves, not in normal tissue like blood or muscle.
The key concern with both Ollier disease and Maffucci syndrome is a meaningfully higher risk of malignant transformation. While a single, solitary enchondroma rarely becomes cancerous, having multiple enchondromas increases the lifetime risk of one of them progressing to chondrosarcoma. People with these conditions need long-term monitoring, typically with periodic imaging to watch for changes in size, pain, or tumor characteristics that could signal a shift toward malignancy.