American Urological Association - Clusters of Benign Urothelial Cells


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Clusters of Benign Urothelial Cells

Image A

Image B

  • When evaluating a urinary cytology specimen, one of the first aspects that need to be established is the means by which the specimen was collected: clean catch/voided vs. brushing/washing.
  • In voided urines, transitional cells are shed singly; in washings/brushings, the cells tend to be aggregated in sheets and clusters (image A) & (image B); however, if there are no fibrovascular cores, these sheets do not represent papillary clusters.
  • Cytologic features to look for:
    • Fibrovascular cores (discussed above).
    • Multinucleation of the cells may be seen as a reactive phenomenon.
    • Nuclear borders should remain smooth, and chromatin is finely dispersed, with occasional small nucleoli.
    • N:C ratio should be <1:2, and there should not be overlapping of nuclei (the cells show "respect" for each other).
    • Look at the background: is it "clean" (think benign), inflammatory (think reactive), or necrotic (think cancer).