Osteoid osteoma
| Osteoid osteoma | |
|---|---|
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| Osteoid osteoma of the trochanter minor: X-ray and MRI with marked sclerosis around the nidus. | |
| Classification and external resources | |
| ICD-10 | D16.9 |
| ICD-O | 9191/0 |
| DiseasesDB | 31488 |
| eMedicine | article/392850 |
| MeSH | D010017 |
An osteoid osteoma is a benign bone tumor that arises from osteoblasts and was originally thought to be a smaller version of an osteoblastoma. Osteoid osteomas tend to be less than 1.5 cm in size. The tumor can be in any bone in the body but are most common in long bones, such as the femur and tibia. They account for 10 to 12 percent of all benign bone tumors. "Osteoid osteomas may occur at any age, and are most common in patients between the ages of 4 and 25 years old. Males are affected approximately three times more commonly than females."
Characterized by being less than 1.5 cm in diameter, osteoid osteomas most frequently occur in young men (Male:Female ratio 3:1) and may occur in any bone of the body, most frequently around the knee but often also seen in the vertebrae, in the long bones and less commonly in the mandible or other craniofacial bones.
Severe pain typically occurs at night, but can also be constant at any time of day. The chief complaint may only be of dull pain which is non radiating and persistent throughout 24 hours but increases significantly at night. Pain tends to be relieved with NSAIDs such as ibuprofen.
On histological examination osteoid osteoma consists of a small (< 1.52 cm), yellowish to red nidus of osteoid and woven bone with interconnected trabeculae, and a background and rim of highly vascularized, fibrous connective tissue. Varying degrees of sclerotic bone reaction may surround the lesion. Benign osteoblastoma is virtually indistinguishable from osteoid osteoma. The usual appearance included a fibrovascular stroma with numerous osteoblasts, osteoid tissue, well-formed woven bone, and giant cells. The osteoblasts were generally small and regular in shape.
The most common symptoms of an Osteoid Osteoma are:
The most common symptom is pain that can be relieved with over the counter pain medication in the beginning. After the benign tumor develops further the pain can not be alleviated with medication and minor to severe swelling starts to occur. Although, in some cases the pain level remains the same for years, and regular NSAIDs intake keeps the pain at bay. The tumor is often found through x-ray imaging. "Conventional radiographs reveal a well-demarcated lytic lesion (nidus) surrounded by a distinct zone of sclerosis" that allow doctors to identify the tumor.
Radiographs in osteoid osteoma typically show a round lucency, containing a dense sclerotic central nidus (the characteristic lesion in this kind of tumor), surrounded by sclerotic bone. The nidus is seldom larger than 1.5 cm.
The lesion can in most cases be detected on CT scan, bone scans and angiograms. Plain radiographs are not always diagnostic. MRI adds little to the CT findings which are useful for localisation. Radionuclide scanning shows intense uptake which is useful for localisation at surgery using a hand held detector, and for confirmation that the entire lesion has been removed.
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