Bladder & urothelial tract

Urothelial carcinoma - invasive

Poorly differentiated variant (including osteoclast rich giant cells)

Last author update: 1 January 2015
Last staff update: 12 November 2021

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PubMed Search: Osteoclast rich undifferentiated carcinoma

Monika Roychowdhury, M.D.
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Cite this page: Roychowdhury M. Poorly differentiated variant (including osteoclast rich giant cells). website. Accessed February 22nd, 2024.
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 #339:

Various images









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Background mononuclear tumor cells

Osteoclast-like giant cell carcinoma

Osteoclast rich undifferentiated urothelial carcinoma

Cytoplasmic immunoreactivity with vimentin

Immunoreactivity with CD68

Focal immunoreactivity with AE1 / AE3

Nuclear immunoreactivity with Ki67

Nuclear immunoreactivity with p53

Osteoclast-like giant cells positive for CD68

Cytology images

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Diff Quick stain

Pap stain

Diff Quick stain

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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