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.