Soft Tissue
Extraskeletal bone tumors
Extraskeletal osteosarcoma

Reviewer: Vijay Shankar, M.D. (see Authors page)

Revised: 10 August 2016, last major update November 2012

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Extraskeletal osteosarcoma [title]
Definition / General
  • Adults, extremities
  • May occur after Xray exposure
  • 60% mortality, worse than chondrosarcoma
  • Subtypes: osteoblastic, chondroblastic, fibroblastic, MFH-like, telangiectactic, well-differentiated (parosteal)
Case Reports
Clinical Images

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Upper arm x-ray



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Skin of lower abdomen

Gross Images

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Case of the Week #370:

Case #1: 75 year old man

Case #2: 55 year old woman



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Retroperitoneal mass

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Upper arm mass

Micro Description
  • Osteoid and bone formation produced by tumor cells, without interposition of cartilage
Micro Images

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Case of the Week #370 - Case #1:

CK negative

Vimentin positive



Case of the Week #370 - Case #2:

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Upper arm, courtesy of Mark R. Wick, M.D.



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Cutaneous tumor on scar of previous bone graft

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Upper arm



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Chest wall

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Retroperitoneal mass

Differential Diagnosis