nephrogenic metaplasia


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  • Clinical

    • hx of surgery, stone, trauma, infection, renal transplant (8%)
    • asymptomatic
    • location: bladder (55%), urethra (51%), ureter (4%), renal pelvis (occasionally)

  • Histology

    • architecture
      • tubular (pink or blue luminal contents) and papillary
      • single layer epithelium
      • edematous and inflammatory fibrovascular cores
    • location: along urothelium
    • cytology
      • single layer cuboidal or low-columnar epithelium
      • can have prominent nucleoli, but lack atypia or mitosis
      • tubules may have hobnail lining
      • may also have clear cells, signet ring cells
    • prominent basement membrane in tubules
    • stroma: inflammation

  • Stains

    • positive: PAX2, PAX8, CK7, racemase
    • negative: high MW CK, p63

  • Ddx

    • prostate adenocarcinoma
      • much stronger and diffuse PSA
    • urothelial carcinoma
      • stratified epithelium
      • delicate fibrovascular cores
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