Bone
Bone forming tumors (not osteosarcoma)
Osteoblastoma

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

Revised: 26 October 2016, last major update August 2013

Copyright: (c) 2003-2016, PathologyOutlines.com, Inc.

PubMed Search: Osteoblastoma[title]

Related topics: Aggressive osteoblastoma
Cite this page: Osteoblastoma. PathologyOutlines.com website. http://pathologyoutlines.com/topic/boneosteoblastoma.html. Accessed December 8th, 2016.
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

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Pubic ramus expanded, cortex thinned

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Contributed by Dr. Mark R. Wick

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Talus - contributed by Dr. Mark R. Wick

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Talus MRI - contributed by Dr. Mark R. Wick



Images hosted on Flickr:
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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



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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

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Osteoblastoma of ilium

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Atypical type - contributed by Dr. Mark R. Wick

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Contributed by Dr. Mark R. Wick



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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

Micro 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)
Micro Images

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Various images

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Atypical type - contributed by Dr. Mark R. Wick

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Atypical type with epithelioid osteoblasts - contributed by Dr. Mark R. Wick


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Contributed by Dr. Mark R. Wick

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Talus - contributed by Dr. Mark R. Wick



Images hosted on Flickr:
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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

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Cytology smears

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