Enchondroma commonly arises from –
**Core Concept**
Enchondromas are benign cartilaginous tumors that arise from the medullary cavity of the bone, specifically from the growth plate cartilage. This is a type of osteochondroma, a tumor that originates from the cartilage and bone matrix.
**Why the Correct Answer is Right**
Enchondromas typically arise from the long bones of the hands and feet, particularly from the phalanges and metacarpals. They are most commonly found in the second and third decades of life. The tumor grows from the cartilage cells within the medullary cavity, leading to an expansion of the bone cortex and sometimes causing cortical thinning. The exact cause of enchondromas is unknown, but genetic factors may play a role.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not specified, but enchondromas do not typically arise from the periosteum or the surface of the bone.
**Option B:** While enchondromas can occur in any long bone, they are most commonly found in the hands and feet, not the spine or pelvis.
**Option C:** This option is not specified, but enchondromas are not typically associated with the synovial joints or the joint capsule.
**Clinical Pearl / High-Yield Fact**
Enchondromas can be a component of Ollier disease, a rare genetic disorder characterized by the presence of multiple enchondromas and enchondromatosis, which can lead to bone deformities and growth abnormalities.
**Correct Answer:** C. The long bones of the hands and feet, particularly the phalanges and metacarpals.