title: Atypical pulmonary carcinoid tumour
text: # Atypical pulmonary carcinoid tumour
  
  Atypical pulmonary carcinoid tumour is a subtype of pulmonary carcinoid tumor. It is an uncommon low-grade malignant lung mass that is most often in the central airways of the lung. It is also known as "atypical lung carcinoid tumour", " atypical lung carcinoid" or "moderately differentiated neuroendocrine carcinoma".
  
  It is a more aggressive than typical carcinoid tumors: nodal metastases in 70% vs. 5%. The 5 year survival is 49-69%.
  
  Atypical carcinoid tumors have increased mitotic activity (2-10 per 10 HPF), nuclear pleomorphism or foci of necrosis.
  
  ## Morphological differential diagnosis
  
  * Typical pulmonary carcinoid tumor
     * Typical pulmonary carcinoid lacks comedo-like necrosis, and has < 0.2 mitotic figures/HPF.
  