**Question:** Not true about enchondroma

A. Enchondroma can cause bone pain
B. Enchondroma is a malignant tumor
C. Enchondroma is always associated with an underlying genetic disorder
D. Enchondroma is a rare tumor

**Core Concept:** Enchondroma is a benign cartilage-forming tumor that primarily develops within the bones. It is a solitary or multiple lesion, often seen in long bones and vertebrae. Enchondromas are generally slow-growing and do not cause significant symptoms unless they break through the bone cortex. They are generally considered a precursor to osteosarcoma, but are not malignant themselves.

**Why the Correct Answer is Right:**
Option A is correct because enchondromas are generally asymptomatic and do not cause bone pain unless they grow large enough to put pressure on surrounding tissues or nerves.

Option B is incorrect because enchondromas are benign tumors, meaning they do not have the potential to invade surrounding tissues or spread to other parts of the body. They are considered precursor lesions for osteosarcoma but are not malignant themselves.

Option C is incorrect because not all enchondromas are associated with underlying genetic disorders like Ollier's disease or Maffucci syndrome. Most enchondromas occur sporadically and are not linked to any specific genetic conditions.

Option D is correct because enchondromas are relatively common tumors, often found in young adults and the elderly. They are not extremely rare or unknown lesions.

**Why Each Wrong Option is Incorrect:**

Option A: Enchondromas are generally asymptomatic, meaning they do not cause bone pain as they are slow-growing and do not invade surrounding tissues. They are typically discovered incidentally on imaging studies or during surgery for another reason.

Option B: Enchondromas are benign tumors, meaning they are not malignant and do not have the potential to spread to other parts of the body. They are considered precursor lesions for osteosarcoma, but are not malignant themselves.

Option C: Not all enchondromas are associated with underlying genetic disorders like Ollier's disease or Maffucci syndrome. Most enchondromas occur sporadically and are not linked to any specific genetic conditions.

Option D: Enchondromas are relatively common tumors, often found in young adults and the elderly. They are not extremely rare or unknown lesions and can be found in various bones throughout the body.

**Clinical Pearls:**

1. Enchondromas are often discovered incidentally on imaging studies or during surgery for another reason.
2. Enchondromas are not associated with underlying genetic disorders in most cases.
3. Enchondromas are a common type of benign bone tumor that can be found in various bones throughout the body.
4. Enchondromas are considered precursor lesions for osteosarcoma but are not malignant themselves.