Enchondromas are small benign tumors made up of cartilage that form in the bone beneath the toenail. Enchondromas are the most common bone tumors of the hands and feet and usually are painless. The tumor can involve large portions of the bones, causing thinning of the cortex. This can weaken the bone and cause it to break spontaneously. When enchondromas occur in the small bone in the end of the toe, they can cause pain that may mimic the pain of ingrown toenails.

Ollier's Disease, also known as enchondromatosis, frequently occurs in the small bones in the hands and toes (phalanges) and the long bones behind the phalanges, called metatarsals. This condition is characterized by multiple enchondromas.

Maffucci's Syndrome is a very rare form of enchondromatosis that combines multiple enchondromas in bones anywhere in the body with benign soft tissue tumors (known as hemangiomas), which are associated with blood vessels. This condition tends to appear in the hands and feet, and has a greater tendency toward malignant transformation than Ollier's Disease.

Because they are painless, most enchondromas are discovered when X-rays are taken for another reason. CT scans and MRI can also help in diagnosing enchondromas.

The majority of enchondromas require no treatment. Only in cases where the tumors are aggressive and begin destroying bone tissue do they require further attention, often surgical removal.