True about non-ossifying fibroma of bone -a) Present until 3rd & 4th decadeb) Eccentricc) Prominent sclerotic margind) Histologically giant cell with areolar tissuee) Metaphyseal lesion
**Core Concept**
Non-ossifying fibroma (NOF) is a type of benign fibrous bone lesion that primarily affects the metaphyseal region of long bones, particularly in the lower extremities. It is characterized by a mix of fibrous tissue, woven bone, and cystic areas.
**Why the Correct Answer is Right**
Non-ossifying fibroma typically presents in the first two decades of life, but can also occur in the third and fourth decades. The lesion is usually eccentric, meaning it occurs on one side of the bone, rather than being centrally located. The sclerotic margin is a characteristic radiographic feature of NOF, where a thin layer of dense bone forms around the lesion. The histological appearance of NOF typically shows a mixture of fibrous tissue, woven bone, and cystic areas, but it does not typically contain giant cells or areolar tissue. Metaphyseal involvement is a hallmark feature of NOF.
**Why Each Wrong Option is Incorrect**
* **Option A:** Incorrect because while NOF can occur in the third and fourth decades, it is more commonly seen in the first two decades of life.
* **Option C:** Incorrect because while the sclerotic margin is a characteristic of NOF, it is not the only feature of this lesion.
* **Option D:** Incorrect because giant cells are not a typical feature of NOF, and are more commonly seen in giant cell tumors of bone.
* **Option B:** Incorrect because NOF is typically a metaphyseal lesion, but it can also occur in the diaphysis.
**Clinical Pearl / High-Yield Fact**
Non-ossifying fibroma is a benign bone lesion that is often asymptomatic, but can cause pain and swelling if it grows large enough to compress adjacent bone or soft tissues. It is usually seen in children and adolescents, and is more common in males than females.
**Correct Answer:** e) Metaphyseal lesion