Bone
Bone forming tumors (not osteosarcoma)
Osteoblastoma


Topic Completed: 1 August 2013

Revised: 5 July 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: Osteoblastoma[title]

Related topics: Aggressive osteoblastoma

David R. Lucas, M.D.
Page views in 2018: 7,544
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Cite this page: Lucas DR. Osteoblastoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/boneosteoblastoma.html. Accessed July 19th, 2019.
Definition / general
  • Benign, bone forming tumor comprised of anastomosing trabeculae of osteoid and woven bone rimmed by osteoblasts
  • Rare; 1% of primary bone tumors
Terminology
  • Also called giant osteoid osteoma
Sites
  • Wide skeletal distribution
  • 1 / 3 spine and sacrum
Clinical features
  • Progressive pain, not as intense as with osteoid osteoma
  • Spinal tumors have neurological findings and scoliosis
  • Rarely presents with fever, weight loss, generalized periostitis (“toxic osteoblastoma”, Am J Surg Pathol 1979;3:463)
Diagnosis
  • Radiographic correlation often helpful
Radiology description
  • Demarcated bone tumor with intralesional ossification
  • Mostly nondestructive growth
  • Some have central nidus or nidi
  • Tumors with secondary ABC changes (aneurysmal bone cyst) are expansile
  • Spinal tumors originate in dorsal elements, may secondarily involve vertebral body
  • Up to 25% of radiographs are suspicious for malignancy (AJR Am J Roentgenol 1976;126:321)
Radiology images

AFIP images
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Pubic ramus expanded, cortex thinned


Contributed by Dr. Mark R. Wick
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Talus

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Talus MRI



Contributed by Dr. David R. Lucas
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T7 osteoblastoma with central nidus

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Iliac osteoblastoma with sclerotic rim

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Rib osteoblastoma suspicious for malignancy

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Large periosteal osteoblastoma of femur

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Great toe osteoblastoma

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Osteoblastoma of tooth root



Images hosted on other servers:
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Sphenoid osteoblastoma

Prognostic factors
  • 20% local recurrence
  • Tumor localized near central neural axis have greater morbility and mortality
Case reports
Treatment
  • Curettage, en bloc resection
Gross description
  • Mostly curetted gritty, red fragments of osteoblastoma
  • Intact tumors well demarcated with scalloped edges
  • Often hemorrhagic
  • One or more nidi
Gross images

AFIP images
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Osteoblastoma of ilium


Contributed by Dr. Mark R. Wick
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Atypical type


Contributed by Dr. David R. Lucas
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Osteoblastoma of clavicle

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Spinal T7 osteo-
blastoma with
central nidus
involving pedicle


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Intracortical osteoblastoma of tibia

Microscopic (histologic) description
  • Anastomosing trabeculae of osteoid and woven bone
  • Rimmed by single layer of benign activated osteoblasts
  • Numerous osteoclasts
  • Loose fibrovascular stroma between bone trabeculae
  • Intralesional hemorrhage and secondary ABC common
  • Does not permeate adjacent host trabecular bone
  • Often pagetoid reversal lines
  • Central nidus of dense woven bone in some
  • Low mitotic rate
  • Rare tumors with cartilaginous matrix
  • Rare tumors with degenerative atypia (pseudomalignant osteoblastoma)
Microscopic (histologic) images

AFIP images
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Various images



Contributed by Dr. Mark R. Wick
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Atypical type

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Atypical type with epithelioid osteoblasts


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Talus



Contributed by Dr. David R. Lucas
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Osteoblastoma with cartilaginous matrix

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Demarcated tumor

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Activated osteoblasts

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Anastomosing trabeculae


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Central nidus of sclerotic woven bone

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Solid area of an osteoblastoma

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Osteoblastoma high power

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Degenerative atypia



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Various images

Cytology description
  • Large osteoblasts with eccentric cytoplasm and perinuclear hof and large vesicular nuclei with prominent nucleoli
  • Osteoclastic giant cells
  • Osteoid matrix
Cytology images

Contributed by Dr. David R. Lucas
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Cytology smears
A and B: Plasmacytoid appearance of osteoblast and multinucleated osteoclast cells (Diff-Quik, 3400)
C: Osteoblasts and banal spindled cells (Papanicolaou, 3400)
D: Cell block exhibiting osteoid with osteoblasts (H&E, 3100)

Electron microscopy description
  • Children and young adults
  • Mean age 20 years, wide age range (6 - 75 years)
  • 60% female (2:3 male:female ratio)
Differential diagnosis
Additional references
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