[1564] Serotonin Expression in Pancreatic Neuroendocrine Tumors Correlates with a Trabecular Histologic Pattern and Fewer Lymph Node Metastases.

Chad M McCall, Chanjuan Shi, Alison P Klein, Gunter Kloppel, Bjorn Konukiewicz, Barish H Edil, Trevor Ellison, Ralph H Hruban. The Johns Hopkins University School of Medicine, Baltimore, MD; Technical University of Munich, Germany

Background: We recently described a small series of pancreatic neuroendocrine tumors (PanNETs) with prominent stromal fibrosis and serotonin expression. In order to better understand the relationship between tumor histopathological patterns and serotonin expression, we identified all pancreatic NETs with significant stromal fibrosis over the past thirty years at our institution.
Design: All available slides from 361 PanNETs diagnosed at our institution from 1980-2009 were reviewed for prominent stromal fibrosis. 52 cases were identified, and these neoplasms were immunolabeled with antibodies to serotonin and Ki-67. Histology and serotonin and Ki-67 immunoreactivity were examined for each case.
Results: At least focal serotonin immunoreactivity was found in 14 of 52 (26.9%) of the fibrotic PanNETs studied. Two predominant histologic subtypes were identified: 14 of 52 (26.9%) had a trabecular or trabecular-glandular cellular pattern interspersed by fibrosis, while 38 of 52 (73.1%) had a solid architecture. Tumors with predominantly trabecular architecture were significantly more likely to be serotonin-positive (8 of 14 (57.1%)) than those with solid architecture (6 of 38 (15.8%)) (p<0.01). Serotonin-positive tumors were less likely to have lymph node metastases (1 of 13 (7.7%)) than serotonin-negative tumors (17 of 35 (48.6%)) (p=0.026). There was no significant association of serotonin immunoreactivity with Ki-67 proliferation index, tumor size, or the presence of distant metastases.
Conclusions: Our data demonstrate a correlation between trabecular architecture and serotonin immunoreactivity in pancreatic NETs with stromal fibrosis. Serotonin-positive tumors are also less likely to have lymph node metastases. This subset of pancreatic NETs have no significant difference in distant metastatic potential or Ki-67 proliferation index in our series.
Category: Liver & Pancreas

Monday, February 28, 2011 2:45 PM

Platform Session: Section D, Monday Afternoon


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