From the Guidelines
Osteoid osteoma is a benign bone tumor that typically affects young people, particularly males between 10-30 years of age, and is characterized by a small growth called a nidus, which produces prostaglandins causing significant pain. According to the American College of Radiology appropriateness criteria 1, the diagnosis of osteoid osteoma usually involves radiographs, and if radiographs are suggestive of osteoid osteoma, CT without IV contrast is usually appropriate for evaluation. The tumor most commonly affects long bones, particularly the femur and tibia, but can occur in any bone. Some key characteristics of osteoid osteoma include:
- A small (less than 2 cm) growth called a nidus
- Production of prostaglandins causing significant pain, especially at night
- Pain that is typically relieved by nonsteroidal anti-inflammatory drugs (NSAIDs)
- A tendency to affect young people, particularly males between 10-30 years of age Treatment options include conservative management with NSAIDs for pain control, which may be continued for 6-24 months as some tumors resolve spontaneously, or definitive treatment through minimally invasive procedures like radiofrequency ablation or surgical removal, as supported by the latest guidelines 1. The pain mechanism involves prostaglandin production by the tumor, explaining why NSAIDs are particularly effective, and complete removal or destruction of the nidus typically results in immediate pain relief and excellent prognosis with very low recurrence rates.
From the Research
Definition and Characteristics of Osteoid Osteoma
- Osteoid osteoma is a benign bone-forming tumor with the hallmark of tumor cells directly forming mature bone 2.
- It consists of osteoid and woven bone, surrounded by a halo of reactive sclerotic bone, with an average size of the nidus less than 1.5 cm 3.
- Osteoid osteoma is characterized by a radiolucent nidus surrounded by reactive osteosclerosis 4.
Epidemiology and Demographics
- Osteoid osteoma accounts for around 5% of all bone tumors and 11% of benign bone tumors, with a male predilection 2.
- It typically occurs in young males, with a male to female ratio of 3:1, and most commonly between the ages of seven and 25 years 5.
- Osteoid osteoma is the third most common benign bone tumor, usually occurring in the cortex of long bones 4, 6.
Clinical Presentation and Symptoms
- Nocturnal pain is the most common symptom, which usually responds to salicylates and non-steroidal anti-inflammatory medications 2, 4.
- Pain can be dull and aching, worse at night, and often relieved with NSAIDs 5.
- Joint pain with synovitis and joint effusion can occur if the lesion is located near chondral structures, or painful scoliosis if located in the spine 3.
Diagnosis and Treatment
- CT is the modality of choice for diagnosis and specifying the location of the lesion 2.
- Plain radiography and computed tomography are usually sufficient for the diagnosis of osteoid osteoma 4.
- Initial treatment includes salicylates and NSAID, as the tumor often regresses spontaneously over 2-6 years 4.
- Surgical treatment is indicated in case of unresponsive pain to medical therapy, and minimally invasive techniques have replaced open surgery as the gold standard of surgical treatment 4, 6.
- Radiofrequency ablation, interstitial laser ablation, cryoablation, and magnetic resonance-guided focused ultrasound surgery are minimally invasive treatment options, each with their own advantages and pitfalls 6.