Bone & joints
Other osteogenic tumors
Aggressive osteoblastoma


Topic Completed: 1 August 2013

Minor changes: 8 February 2021

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PubMed Search: Aggressive osteoblastoma

Related topics: Osteoblastoma

David R. Lucas, M.D.
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Cite this page: Lucas DR. Aggressive osteoblastoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/boneosteoblastomaaggressive.html. Accessed March 5th, 2021.
Definition / general
  • Rare variant of osteoblastoma characterized by epithelioid osteoblasts, aggressive growth, propensity for local recurrence, yet no metastatic potential
  • Controversial tumor not recognized as a distinct entity by all investigators
Terminology
  • Epithelioid osteoblastoma, epithelioid multifocal osteoblastoma, malignant osteoblastoma
Sites
  • Various skeletal locations: vertebrae, sacrum, pelvis, long bones, skull, small bones of hands and feet
Diagnosis
  • Large epithelioid osteoblasts, locally aggressive behavior
Radiology description
  • Similar to conventional osteoblastoma, but often larger (<4 cm)
  • Osteolytic with sclerotic rim, often with areas of ossification
  • Secondary aneurysmal bone cyst in some
Radiology images

Contributed by David Lucas, M.D.
Expansile tibial tumor with central nidus

Expansile tibial tumor with central nidus



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Pelvic tumor

Case reports
Treatment
  • En bloc resection when feasible
Gross description
  • Generally well demarcated expansile mass with rounded contours
  • Red, friable, gritty
  • Ossification and hemorrhage
  • Usually > 4 cm
Gross images

Contributed by David Lucas, M.D.
Expansile, demarcated tibial tumor with central nidus and intralesional hemorrhage

Expansile, demarcated tibial tumor with central nidus and intralesional hemorrhage

Microscopic (histologic) description
  • Anastomosing bone trabeculae
  • Loose fibrovascular stroma
  • Large, epithelioid osteoblasts arranged in single cell layers and aggregates, which are twice the size of normal osteoblasts
  • Osteoblasts have abundant eosinophilic cytoplasm, eccentric vesicular nuclei with prominent nucleoli
  • Mitosis and necrosis usually not seen
Microscopic (histologic) images

Contributed by David Lucas, M.D. and AFIP images
Epithelioid multifocal pattern

Epithelioid multifocal pattern

Sheets of large, epithelioid osteoblasts

Sheets of large, epithelioid osteoblasts

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Various images



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Sheet of epithelioid osteoblasts

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Immature trabeculae with osteoblastic rimming

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Zonation of bone formation

Molecular / cytogenetics description
Electron microscopy description
  • Slightly older age group than conventional osteoblastoma, third - fourth decade
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