Lung tumor
Neuroendocrine tumors
Atypical carcinoid


Topic Completed: 1 September 2012

Minor changes: 18 December 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: Atypical carcinoid[TI] lung

Deepali Jain, M.D.
Page views in 2019: 7,227
Page views in 2020 to date: 2,750
Cite this page: Jain D. Atypical carcinoid. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungtumoratypicalcarcinoid.html. Accessed June 1st, 2020.
Definition / general
  • 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%
Microscopic (histologic) description
  • Carcinoid tumors with increased mitotic activity (2-10 per 10 HPF), nuclear pleomorphism or foci of necrosis
Microscopic (histologic) images

Images hosted on other servers:

Various images

Various immunostains with various tumors


Atypical carcinoid tumor of lung metastatic to adrenal gland

Positive stains
Negative stains
Electron microscopy description
  • Numerous large neurosecretory granules
Differential diagnosis
Back to top