Journal of Pathology and Translational Medicine

Original Article

SSTR2A Protein Expression in Neuroendocrine Neoplasms of the Colorectum.: Young Eun Kim, Jeeyun Lee, Young Suk Park, Kyoung Mee Kim; Korean J Pathol. 2011;45(3):276-280.; DOI: https://doi.org/10.4132/KoreanJPathol.2011.45.3.276

Abstract PDF: BACKGROUND
Expression studies of somatostatin receptor type 2A (SSTR2A) in neuroendocrine neoplasms (NENs) led to the development of clinically relevant diagnostic and therapeutic strategies. However, most of these strategies used in-house-developed antibodies and were focused on lung tumors. We evaluated commercially available SSTR2A antibodies in NENs of the colorectum to observe their subcellular localization and distribution within the resected tumor.
METHODS
The immunohistochemistry of 77 NENs located in the colorectum were studied using a commercially available antibody against SSTR2A.
RESULTS
Most neuroendocrine tumors (NET) grade (G)1 and G2 expressed the SSTR2A in the cytoplasm with apical or luminal localization. However, all neuroendocrine carcinomas (NEC) G3 were negative for SSTR2A.
CONCLUSIONS
Our data indicate that SSTR2A immunohistochemistry shows cytoplasmic staining with distinct subcellular localization in most NET G1 in the colorectum using a commercially available antibody. Low or no expression of SSTR2A in NET G2 and NEC G3 raises the possibility that SSTR2A may correlate with histologic differentiation and proliferative activity. Further validation studies in large case series are needed.

Case Reports

Somatostatin Secreting Islet Cell Adenoma: A case report.: Tae Sook Kim, Je G Chi; Korean J Pathol. 1996;30(7):630-634.

Abstract PDF: Somatostatin secreting islet cell adenoma(somatostatinoma) of the pancreas is a rare entity. Less than 30 cases of pancreatic somatostatinoma could be searched in the world literature. We present a case of somatostatinoma of the pancreas in a 64-year-old woman. This patient had suffered from diabetes, cholelithiasis and intermittent diarrhea. Laboratory examination revealed steatorrhea, blood somatostatin level of 30 pg/ml, and fasting blood glucose level of 116 mg/dl. Subtotal pancreatectomy was done after radiological demonstrations of a round tumor mass in the pancreas. It was a 2 cm-sized well demarcated yellowish brown round solid mass located in the proximal pancreas. A retention cyst was seen just distal to the tumor. Histologically, tumor masses consisted of polygonal cells with distinct cell border, having granular eosinophilic cytoplasm and small bland looking nuclei. The tumor cells were arranged in small solid islands and trabeculae, separated by fibrovascular stroma. Immunohistochemical stain for somatostatin was positive in the cytoplasm of the individual tumor cell, and ultrastructurally variable sized membrane bound electron dense granules of 200 nm in average diameter were found in tumor cells.

Duodenal Somatostatinoma: A case report.: Mee Hye Oh, Yi Kyeong Chun, Hye Jae Cho, Jin Ho Lee, Hong Yong Kim, Ill Hyang Ko; Korean J Pathol. 1993;27(6):645-649.

Abstract PDF: Somatostatinoma is rare endocrine tumor that was first described in 1977 by Ganda et al. and Larsson et al. simultaneously. It seems nonfunctioning at clinical level. But it may present with diabetes, diarrhea, cholelithiasis, steatorrhea, indigestion, hypochlorhydria, and anemia. In contrast with pancreatic somatostatinoma, duodenal somatostatinoma, in general, is clinically silent. Duodenal endocrine tumors show similar histologic pattern. Therefore, the definite diagnosis is performed by immunohistochemistry and electron microscopic examination. We have experienced a case of somatostatinoma of duodenum in a 62-year-old male. He has complained generalized pruritus for one year and jaundice for 2 weeks. Grossly, the mass was a intraluminary protruding, polypoid lesion with focal mucosal erosion at immediately distal to Ampulla of Vater. Histologically, it showed tall, cylindrical cells with distinct cell membranes, having granular cytoplasm and small innocent looking nuclei. No mitosis was seen. The tumor cells were arraged in small solid groups and trabeculae, separated by fibrovascular stroma. Immunohistochemically, the tumor cells were strongly positive with somatostatin and negative with several other hormonal and neuroendocrine markers. Ultrastructurally, the cytoplasm contains numerous, homogeneous low electron dense secretory granules, which are essentially similar to those seen in normal delta cells.

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