American Urological Association - Carcinoid Tumor (Monodermal Teratoma)
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Carcinoid Tumor (Monodermal Teratoma)

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  • Carcinoid of the testis is considered a monodermal teratoma.
  • 20% are associated with other teratomatous elements.
  • In general occurs in older patients than GCT (10-83 years, mean 46).
  • Carcinoid syndrome is rare, but when it occurs it predicts increased likelihood of metastatic disease.
  • Serum AFP and HCG are normal; 5-HIAA elevated.
  • Gross: solid well-circumscribed yellow-tan nodule; cystic component.
  • Histology:
    • Monotonous cells with abundant eosinophilic cytoplasm and characteristic "salt and pepper" chromatin (image A) & (image B).
    • Growth pattern is nested, or may show a "ribbon and festooning" appearance.
    • ITGCN rare in pure carcinoid.
  • Immunohistochemistry: neuroendocrine markers synaptophysin+ and chromogranin+.
  • DDX: primary testicular carcinoid (20% with teratomatous elements) vs. metastatic carcinoid (bilateral, microvascular invasion, and extratesticular involvement).
  • Prognosis excellent with localized disease; excision is curative.