Bladder, ureter & renal pelvis
Urothelial carcinoma-invasive
Poorly differentiated variant (including osteoclast rich giant cells)

Topic Completed: 1 January 2015

Minor changes: 11 June 2020

Copyright: 2003-2020,, Inc.

PubMed Search: Osteoclast rich undifferentiated carcinoma

Monika Roychowdhury, M.D.
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Page views in 2020 to date: 838
Cite this page: Roychowdhury M. Poorly differentiated variant (including osteoclast rich giant cells). website. Accessed August 7th, 2020.
Definition / general
  • Extremely rare variant of high-grade urothelial carcinoma with an aggressive behavior and poor outcome
  • Composed of a mixture of undifferentiated mononuclear carcinoma cells and osteoclast-like reactive giant cells (Mod Pathol 2006;19:161)
  • Mostly men in their 7th to 9th decade of life
Clinical features
  • Usually gross hematuria, may present with flank pain, renal colic and dysuria
Case reports
Gross images

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Tumor of distal ureter

Microscopic (histologic) description
  • Composed of a mixture of mononuclear malignant epithelial cells and multinucleated osteoclast-like reactive giant cells
  • Mononuclear cells have abundant cytoplasm, round to oval vesicular nuclei, mild atypia and variable mitotic activity
  • The giant cells are morphologically and immunohistochemically identical to osteoclasts and are regarded as being of histiocytic origin; are cytologically bland, may exhibit phagocytic activity but no mitotic activity; are generally evenly distributed among mononuclear cells but may condense around hemorrhagic foci
Microscopic (histologic) images

Case of the Week #339:

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Various H&E images

Various immunostains

Cytology images

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Various images

Differential diagnosis
  • Giant cell carcinoma: obvious malignant bizarre giant cells, mitotic activity, invasion, positive staining for epithelial markers
  • Foreign-body type giant cell reaction: inflammatory infiltrate, no atypia, no invasion
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