Osteoid Osteoma: Causes

Pathogenesis (disease development)

Osteoid osteoma originates from osteoblasts (bone-forming cells) and thus is one of the osseous tumors. It consists of a small nidus (focus; a few mm to <1.5 cm) that contains the pathologic (diseased) cells. The nidus is a well-vascularized (vascularized/strongly vascularized), osteoblastic area. It is from this area that pain emanates, as it synthesizes (produces) prostaglandins (tissue hormones that can also trigger pain, among other things). Around it one finds a strong reactive, sclerotic (condensed) ossification (ossification).

The osteoid osteoma is centrally located in the cortical (outer layer of bone). The growth is self-limiting. If the osteoid osteoma is larger than 1.5 cm, it is called an osteoblastoma.

Etiology (causes)

The exact causes of osteoid osteoma are still unclear.