Abstract
BackgroundGangliocytic paraganglioma (GP) is an extremely rare benign tumor that commonly arises from the second part of the duodenum. Since GP exhibit neither prominent mitotic activity nor Ki-67 immunoreactivity, this tumor is often misdiagnosed as neuroendocrine tumor (NET) G1 (carcinoid tumor). However, patients with GP may have a better prognosis than patients with NET G1. This fact emphasizes the importance of differentiating GP from NET G1, but few studies have reported the epidemiology and histopathology of GP because of its rarity. To differentiate GP from NET G1 with ease, we conducted a multi-institutional retrospective study analyzing the morphometric and immunohistochemical features of this tumor.MethodsSince only a limited number of patients with GP could be identified in our institute, we conducted a multi-institutional retrospective study of GP in Japan, which was approved by the Ethics Committee of our medical institute. The obtained tissue sections underwent detailed morphometric and immunohistochemical analyses. Additionally, to differentiate GP from NET G1 with ease, immunohistochemical findings were compared.ResultsIn our examination of 12 cases of duodenal GP, we found that epithelioid cells of GP exhibited positive reactivity for progesterone receptor and pancreatic polypeptide, whereas tumor cells of NET G1 were completely negative reactivity for both. Additionally, although GP is considered to be an extremely rare NET, we found that four (40.0%) of the ten patients at our institute with duodenal NET G1 actually had GP.ConclusionsAlthough GP is regarded as a rare NET, our results suggest that it accounts for a substantial percentage of duodenal NETs. Additionally, confirmation of immunoreactivity for progesterone receptor and pancreatic polypeptide can assist in differentiating GP from NET G1.
Highlights
Gangliocytic paraganglioma (GP) is an extremely rare benign tumor that commonly arises from the second part of the duodenum
Collection of gangliocytic paraganglioma cases Sample collection from our institute As GP is a rare neuroendocrine tumor (NET) that commonly arises from the duodenum, we searched for cases of duodenal NET that were recorded between January 2000 and August 2013 using pathologic diagnosis support software (‘Dr Helper’ System, JR West Japan Railway Company, Osaka, Japan)
Ten of the 11 patients exhibited fewer than two mitoses per 10 High-power field (HPF) and a Ki-67 labeling index of less than 2%
Summary
Gangliocytic paraganglioma (GP) is an extremely rare benign tumor that commonly arises from the second part of the duodenum. Patients with GP may have a better prognosis than patients with NET G1 This fact emphasizes the importance of differentiating GP from NET G1, but few studies have reported the epidemiology and histopathology of GP because of its rarity. Gangliocytic paraganglioma (GP) is an extremely rare neuroendocrine tumor (NET) that commonly arises from the second part of the duodenum [1,2]. In 2010 the World Health Organization (WHO) updated their classification of NET arising from the digestive system [5,6] This WHO classification proposed a grading system for NET based on the proliferative activity of tumor cells, which is defined by the number of mitoses confirmed per 10 high-power microscopic fields, or, by the percentage of tumor cells showing positive
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