Osteoma Osteoide

It is a benign osteoblastic lesion characterized by its small size, usually less than one centimeter, with well-defined borders and the usual presence of a peripheral area of ​​reactive bone formation. Also known as Brodie's abscess, localized osteitis fibrosa, or Jaffe tumor, it represents 10% of benign bone tumors. It usually presents in 80% of cases between 5 and 25 years of age. Osteoid osteomas are not locally aggressive and do not undergo malignant transformation. Fifty percent of them are located in the long bones of the lower extremities very close to the end of the diaphysis. In the upper extremity, they are most frequently located in bones near the elbow. The neck of the femur is the most common isolated location. Diagnosis is based on clinical, imaging, and histological elements. The main symptom is pain, usually nocturnal in 98% of cases, which is relieved with salicylates or nonsteroidal anti-inflammatory drugs, but this is not always the case. Pain relief is related to the inhibitory action of prostaglandins. The most commonly found prostaglandins are E2, F, and alpha, which produce a vasodilatory effect that in turn triggers the proliferation of blood vessels and increases pressure on the tumor. Inflammation is the second most common symptom. When it is located in the spine, it can mimic a herniated disk and is the most common cause of painful scoliosis in adolescents. Other symptoms found include muscle atrophy and gait disturbances. The most commonly used imaging tests are plain X-ray, computed tomography, magnetic resonance imaging, bone scan, and positron emission tomography. Macroscopically, the lesion is a small, rounded or oval lesion known as the tumor nidus. It is reddish-brown in color and has a variable consistency, which can be soft, granular, or sclerotic. Sclerosis is accentuated toward the central area of ​​the tumor. Microscopy reveals newly formed bone trabeculae and osteoid tissue nestled within highly vascularized osteogenic connective tissue surrounded by sclerotic tissue with well-oriented thick trabeculae. Fibroblasts, osteoblasts, and some giant cells are identified in the tissue. Differential diagnosis includes entities with similar clinical, imaging, and histological characteristics, such as osteoblastoma, chondroblastoma, bone infarction, Brodie's abscess, and stress fracture. Conservative treatment is a reasonable option, especially in anatomical locations that are difficult to approach surgically. The surgical treatment of choice is en bloc resection. However, it has the following disadvantages: restricted weight-bearing and physical activity in the case of lower extremity involvement, potential risk of pathological fracture, and the need for bone grafting with internal fixation. Other less invasive treatment modalities exist, such as CT-guided radiofrequency, ethanol injection, and photocoagulation. The main complications are limb discrepancy, recurrence in 4.5% of cases, and complications related to treatment with radiofrequency or other less invasive methods.