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Small Cell Carcinoma

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  • Rare, comprises 1% of all prostate cancer.
  • May occur pure or mixed with acinar adenocarcinoma.
  • ~1/2 of patients have history of acinar adenocarcinoma, and some with prior hormonal treatment.
    • Neuroendocrine cells are devoid of androgen receptors; ADT may lead to clonal progression.
  • Presents with rapid onset urinary tract obstruction, dysuria, nocturia, or urgency and some may present with paraneoplastic syndromes.
  • Serum PSA level variable, may be normal.
  • Histology:
    • Indistinguishable from small cell carcinoma of other organs such as lung and bladder.
    • Sheets of small round blue cells that infiltrate in a diffuse pattern (image A), (image B), (image C).

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    • Cells have nuclei with "salt and pepper" chromatin (dusty appearance with inconspicuous nucleoli).
    • Crush artifact (smearing of cells) and nuclear molding is common.
    • High mitotic activity, apoptosis and necrosis common.
  • Immunohistochemistry: positive for neuroendocrine markers synaptophysin (image D) and chromogranin.
  • Most patients present with EPE, large tumor, advanced stage, and distant metastasis.
  • Poor prognosis with mean survival of <1 year after development of SCC component.
  • No difference in prognosis between pure SCC and those SCC mixed with acinar adenocarcinoma.