Final answer:
An osteoid osteoma is a benign bone tumor. It appears as a small, round, dark lesion on imaging, often surrounded by a zone of hardened bone. It commonly causes localized pain that intensifies at night.
Step-by-step explanation:
An osteoid osteoma is a benign bone tumor that typically appears as a small, round, radiolucent (dark) lesion on an X-ray or other imaging technology. This lesion is usually about 1 to 2 cm in diameter and has a central region known as the nidus, which is an area of immature bone or osteoid. Surrounding the nidus, there is often a zone of reactive bone sclerosis (hardening). This kind of appearance is particularly typical of osteoid osteomas located in long bones, the spine, or the pelvis. Clinical symptoms typically include localized pain that tends to intensify at night and is often relieved by nonsteroidal anti-inflammatory drugs (NSAIDs).
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