Pathogenesis (disease development)
Osteoblastomas originate from osteoblasts (bone-forming cells) and thus are classified as osseous tumors. Their nidus (focus) is between 1.5 and 2 cm (even > 2 cm) in size, making it larger than the comparable osteoid osteoma (< 1.5 cm). It is a well-vascularized (vascularized/strongly vascularized) area.
In contrast to osteoid osteoma, reactive sclerotic (compacted) ossification, also called marginal sclerosis, is absent or sparse around the nidus in osteoblastoma. Osteoblasts distributed throughout the nidus produce osteoid (“immature bone”) and disorganized (primitive) woven bone.
Osteoblastomas are localized in the cancellous region of the bone. Their growth is not self-limiting, so osteoblastomas grow more destructively (destructive/displacing) compared with osteoid osteomas.
Etiology (causes)
The exact causes of osteoblastomas are still unclear.
