True about osteoid osteoma is
**Core Concept**
Osteoid osteoma is a benign bone tumor that typically affects the long bones of the lower extremities. It is characterized by a small, usually less than 2 cm, nidus surrounded by a zone of sclerosis.
**Why the Correct Answer is Right**
Osteoid osteoma is known for its classic presentation of night pain that is relieved by NSAIDs, which is attributed to the production of prostaglandins and other vasoactive substances by the tumor. This pain is due to the release of prostaglandins, which sensitize the surrounding bone to pain.
**Why Each Wrong Option is Incorrect**
**Option A:** This option may refer to the fact that osteoid osteoma is not typically painful at rest, which is incorrect. However, this is not a clear distractor.
**Option B:** Osteoblastoma is a different type of benign bone tumor that is larger and more aggressive than osteoid osteoma.
**Option C:** Osteoid osteoma is not typically associated with cortical destruction or a significant soft tissue mass, unlike some other bone tumors.
**Clinical Pearl / High-Yield Fact**
A key characteristic of osteoid osteoma is its characteristic "nidus" surrounded by a zone of sclerosis, which can be visualized on X-rays or CT scans.
**Correct Answer: B. Osteoblastoma.**