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Lung tumor

Carcinoid and related tumors

Atypical carcinoid tumor

Reviewer: Deepali Jain, M.D. (see Reviewers page)
Revised: 9 January 2013, last major update September 2012
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.


● Also called moderately differentiated neuroendocrine carcinoma
● Diagnostic criteria (Rosai): resembles a carcinoid but with atypical features
● More aggressive than typical carcinoid tumors: nodal metastases in 70% vs. 5%
● 5 year survival is 49-69%

Micro description

● Carcinoid tumors with increased mitotic activity (2-10 per 10 HPF), nuclear pleomorphism or foci of necrosis

Micro images

Various images

Various immunostains with various tumors

Atypical carcinoid tumor of lung metastatic to adrenal gland

Positive stains

● More intense neuroendocrine staining than small cell carcinoma
● Also positive for pancreatic polypeptide
● FoxM1(+), p27/kip1 (high, Histopathology 2012;60:731)
● Coexpression of PAX5 with c-Met (Arch Pathol Lab Med 2010;134:1702)

Negative stains

● Enhancer of zeste homolog 2 (Hum Pathol 2011;42:867)
● Collapsin response mediator protein (CRMP5, Am J Surg Pathol 2008;32:1699)

Electron microscopy description

● Numerous large neurosecretory granules

Differential diagnosis

Carcinoid tumor: lacks comedo-like necrosis, has < 0.2 mitotic figures/HPF (Lung Cancer 2011;71:34)

End of Lung tumor > Carcinoid and related tumors > Atypical carcinoid tumor

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