[578] Serotonin-Producing EC-Cell Tumors of the Pancreas. Morphological, Immunohistochemical, Ultrastructural and FISH Study of 15 Cases and Comparison with Intestinal EC-Cell Tumors.

Stefano La Rosa, Aurel Perren, Anja Schmitt, Luca Albarello, Barbara Bernasconi, Giovanna Finzi, Carlo Capella. Ospedale di Circolo, Varese, Italy; University of Berne, Switzerland; San Raffaele Scientific Insitute, Milan, Italy; University of Insubria, Varese, Italy

Background: Serotonin-producing tumors of the pancreas (5HT-PETs) are rare neoplasms composed of EC-cells which have been mainly described in the literature as case reports. Studies analyzing the clinico-pathological features of a consistent number of such pancreatic endocrine tumors, also investigating the similarities to and differences from intestinal EC-cell tumors, have never been reported.
Design: The morphological, immunohistochemical, ultrastructural and FISH features of 15 pancreatic and 20 intestinal serotonin-producing neoplasms were compared. In addition, a review the literature on 5HT-PETs has been performed to better understand the clinico-pathological features of this rare tumor type.
Results: Tumors of the present series were not associated with the carcinoid syndrome. The lack of substance P and acidic fibroblast growth factor immunoreactivity, the low immunohistochemical expression of CDX2, VMAT1, connective tissue growth factor and prostatic acid phosphatase, the low positivity for the diazonium reaction, the lack of S100-positive sustentacular cells, the strong expression of VMAT2, and peculiar ultrastructural features characterized 5HT-PETs and differentiated them from intestinal ones, although both categories showed similar chromosome 18 cytogenetic alterations mainly consisting in monosomic clones for chromosome 18. The review of the literature indicated that pancreatic 5HT-functioning tumors (associated with the carcinoid syndrome) arose in younger patients, were larger, more frequently malignant and more aggressive neoplasms than pancreatic 5HT-nonfunctioning ones.
Conclusions: The results suggest that 5HT-PETs show an immunohistochemical and ultrastructural profile more similar to that of gastric EC-cells, rather than intestinal EC1-cells, and show several different morphological features from the related intestinal tumors, although both categories present similar cytogenetic alterations on chromosome 18. 5HT-PETs are more frequently endocrinologically nonfunctioning. The distinction between functioning and nonfunctioning neoplasms is of clinical relevance since the former are more frequently malignant and associated to a worse patient survival.
Category: Endocrine

Tuesday, March 1, 2011 1:00 PM

Poster Session IV # 52, Tuesday Afternoon


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