Typical carcinoid tumor (IMAGE)
Caption
(a) Tumor cells are uniform with round to oval nuclei and inconspicuous nucleoli, arranged in a nested/organoid pattern. Other growth patterns include pseudoglandular, trabecular, and follicular with rosette formation. There is moderate to abundant eosinophilic cytoplasm (×20). (b) Tumor cells typically show immunoreactivity to CAM5.2, which is helpful to distinguish carcinoid tumor from paraganglioma (×10). (c) TTF-1 would help establish a pulmonary lineage and tend to be focal and weak (×20). Neuroendocrine markers (d) synaptophysin and (e) chromogranin are positive in tumor cells (×20), and (f) proliferation labeling index with Ki-67 should be low in typical carcinoid tumor (×20).
Credit
Haodong Xu, Liang Lu
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