title: Poorly differentiated neuroendocrine carcinomas of the pancreas: a clinicopathologic analysis of 44 cases.
abstract: BACKGROUND
  In the pancreas, poorly differentiated neuroendocrine carcinomas include small cell carcinoma and large cell neuroendocrine carcinoma and are rare; data regarding their pathologic and clinical features are very limited.
  
  
  METHODS
  A total of 107 pancreatic resections originally diagnosed as poorly differentiated neuroendocrine carcinomas were reassessed using the classification and grading (mitotic rate/Ki67 index) criteria put forth by the World Health Organization in 2010 for the gastroenteropancreatic system. Immunohistochemical labeling for neuroendocrine and acinar differentiation markers was performed. Sixty-three cases were reclassified, mostly as well-differentiated neuroendocrine tumor (NET) or acinar cell carcinoma, and eliminated. The clinicopathologic features and survival of the remaining 44 poorly differentiated neuroendocrine carcinomas were further assessed.
  
  
  RESULTS
  The mean patient age was 59 years (range, 21 to 82 y), and the male/female ratio was 1.4. Twenty-seven tumors were located in the head of the pancreas, 3 in the body, and 11 in the tail. The median tumor size was 4 cm (range, 2 to 18 cm). Twenty-seven tumors were large cell neuroendocrine carcinomas, and 17 were small cell carcinomas (mean mitotic rate, 37/10 and 51/10 HPF; mean Ki67 index, 66% and 75%, respectively). Eight tumors had combined components, mostly adenocarcinomas. In addition, 2 tumors had components of well-differentiated NET. Eighty-eight percent of the patients had nodal or distant metastatic disease at presentation, and an additional 7% developed metastases subsequently. Follow-up information was available for 43 patients; 33 died of disease, with a median survival of 11 months (range, 0 to 104 mo); 8 were alive with disease, with a median follow-up of 19.5 months (range, 0 to 71 mo). The 2- and 5-year survival rates were 22.5% and 16.1%, respectively.
  
  
  CONCLUSIONS
  Poorly differentiated neuroendocrine carcinoma of the pancreas is a highly aggressive neoplasm, with frequent metastases and poor survival. Most patients die within less than a year. Most (61%) are large cell neuroendocrine carcinomas. Well-differentiated NET and acinar cell carcinoma are often misdiagnosed as poorly differentiated neuroendocrine carcinoma, emphasizing that diagnostic criteria need to be clearly followed to ensure accurate diagnosis.
authors: Departments of *Pathology ***Surgery †††Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY †Department of Pathology, The Sol Goldman Pancreatic Cancer Research Center ‡‡‡Department of Surgery, Johns Hopkins University, Baltimore, MD ‡Department of Pathology, Emory University, Atlanta, GA §Department of Pathology, Penn State Hershey MC, Hershey ∥Department of Pathology, University of Pittsburgh, Pittsburgh, PA **Department of Pathology, Ohio State University, Columbus ††Department of Pathology, Cleveland Clinic, Cleveland, OH ‡‡Department of Pathology, Mayo Clinic, Rochester, MN §§Department of Pathology, University of Michigan, Ann Arbor, MI ∥∥Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA ¶¶Department of Pathology, Indiana University, Indianapolis, IN ##Department of Pathology, Vanderbilt University, Nashville, TN §§§Department of Pathology, Massachusetts General Hospital, Boston, MA ¶Department of Pathology, Ospedale di Circolo, Varese, Italy #Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
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mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018278:Carcinoma, Neuroendocrine / Q000401:mortality* / Q000473:pathology*; D002454:Cell Differentiation; D018450:Disease Progression; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000401:mortality* / Q000473:pathology*; D016016:Proportional Hazards Models; D055815:Young Adult