Table of Contents
Definition / general | Epidemiology | Sites | Pathophysiology | Clinical features | Diagnosis | Radiology description | Prognostic factors | Case reports | Treatment | Radiology images | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Molecular / cytogenetics description | Differential diagnosisCite this page: Lucas DR. Osteoid osteoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/boneosteoidosteoma.html. Accessed March 4th, 2021.
Definition / general
- Small, benign, bone forming tumor associated with pain and limited growth potential
- Nidus < 1.5 cm (any larger size arbitrarily considered to be an osteoblastoma)
Epidemiology
- Children, adolescents and young adults (most patients 5 - 24 years old)
- Male:female ratio 3:1
Sites
- Long bones, especially femur and tibia (50%) most common
- Virtually any bone can be affected
Pathophysiology
- Pain due to production of prostaglandin E2 or nerve fibers in reactive zone (Mod Pathol 1998;11:175)
Clinical features
- Intense localized pain, worse at night, relieved by NSAIDs
- Juxta - articular tumors with arthritis or joint dysfunction
- Vertebral tumors with scoliosis
Diagnosis
- Intense pain and classic radiographic features
Radiology description
- Nidus usually < 1 cm
- Nidus may be radiolucent or ossified and surrounded by a radiolucent halo
- Usually surrounded by dense, reactive osteosclerosis
- Intracortical, subcortical, medullary or bone surface locations
- Long bone tumors often intracortical
- Vertebral tumors in neural arch
Prognostic factors
- Recurrence is rare
- Incompletely excised tumors can recur
Case reports
- 7 year old boy with metachronous osteoid osteomas of tibia and T7 (J Bone Joint Surg Am 2011;93:e73)
- 18 year old woman with calcanial tumor mimicking arthritis (J Foot Ankle Surg 2012;51:237)
Treatment
- CT localization with excision or radiofrequency ablation, or medical management alone (J Bone Joint Surg Am 1992;74:179)
Radiology images
Gross description
- Small circumscribed nidus with surrounding sclerosis (intact specimen)
- Most often received as red, gritty fragments post curettage
Gross images
Microscopic (histologic) description
- Small, circumscribed
- Anastomosing, irregular trabeculae or solid, sclerotic nidus of woven bone with variable mineralization
- Rimmed by single layer of osteoblasts plus frequent osteoclasts
- Loose, fibrovascular stroma
- Surrounded by thick sclerotic bone
- Lymphoplasmacytic synovitis with juxta - articular tumors
Microscopic (histologic) images
Molecular / cytogenetics description
- Structural alterations involving 22q13.1 identified in two cases (Cancer Genet Cytogenet 2001;124:127)
Differential diagnosis
- Osteoblastoma
- Osteosarcoma
- Reactive bone