Bone
Bone forming tumors (not osteosarcoma)
Osteoid osteoma

Author: David Lucas, M.D. (see Authors page)

Revised: 16 August 2018, last major update August 2013

Copyright: (c) 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: Osteoid osteoma[title]
Cite this page: Lucas, D. Osteoid osteoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/boneosteoidosteoma.html. Accessed October 19th, 2018.
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
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
Treatment
Radiology images

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AFIP images:
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Phalanx

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Femoral neck


Contributed by Dr. Mark R. Wick:
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Femur

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Talus



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Femur; coronal CT scan shows a radiolucent nidus

Gross description
  • Small circumscribed nidus with surrounding sclerosis (intact specimen)
  • Most often received as red, gritty fragments post curettage
Gross images

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AFIP images:
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Femur


Contributed by Dr. Mark R. Wick:
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Femur

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Various images



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Nidus and surrounding sclerosis

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Fibula

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

Images hosted on PathOut server:

Contributed by Dr. Mark R. Wick:
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Foot

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Various images



AFIP images:
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Vascular, loosely fibrous stroma

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Mature osteoid osteoma

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Irregular bony trabeculae

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Synovitis

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Femur



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With anastomosing trabeculae of woven bone

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High power

Molecular / cytogenetics description
Differential diagnosis