Nonfunctioning pancreatic endocrine tumor with extension into the main pancreatic duct: report of a case

Rare Solid Pancreatic Lesions on Cross-Sectional Imaging

Several solid lesions can be found within the pancreas mainly arising from the exocrine and endocrine pancreatic tissue. Among all pancreatic malignancies, the most common subtype is pancreatic ductal adenocarcinoma (PDAC), to a point that pancreatic cancer and PDAC are used interchangeably. But, in addition to PDAC, and to the other most common and well-known solid lesions, either related to benign conditions, such as pancreatitis, or not so benign, such as pancreatic neuroendocrine neoplasms (pNENs), there are solid pancreatic lesions considered rare due to their low incidence. These lesions may originate from a cell line with a differentiation other than exocrine/endocrine, such as from the nerve sheath as for pancreatic schwannoma or from mesenchymal cells as for solitary fibrous tumour. These rare solid pancreatic lesions may show a behaviour that ranges in a benign to highly aggressive malignant spectrum. This review includes cases of an intrapancreatic accessory spleen, pancreatic tuberculosis, solid serous cystadenoma, solid pseudopapillary tumour, pancreatic schwannoma, purely intraductal neuroendocrine tumour, pancreatic fibrous solitary tumour, acinar cell carcinoma, undifferentiated carcinoma with osteoclastic-like giant cells, adenosquamous carcinoma, colloid carcinoma of the pancreas, primary leiomyosarcoma of the pancreas, primary and secondary pancreatic lymphoma and metastases within the pancreas. Therefore, it is important to determine the correct diagnosis to ensure optimal patient management. Because of their rarity, their existence is less well known and, when depicted, in most cases incidentally, the correct diagnosis remains challenging. However, there are some typical imaging features present on cross-sectional imaging modalities that, taken into account with the clinical and biological context, contribute substantially to achieve the correct diagnosis.

Hyperammonemic Encephalopathy in a Patient with Pancreatic Neuroendocrine Tumor and Portosystemic Shunt

Hyperammonemia can lead to encephalopathy and may be accompanied by a diagnostic dilemma. Imaging as well as biochemical analyses are the cornerstone for identifying possible underlying causes such as severe liver disease or urea cycle defect. We report a case of a patient that presented with neurological deficits based on hyperammonemia in the presence of a large pancreatic neuroendocrine tumor (PNET) and portosystemic shunts in the liver. Prior cases are rather scarce, and the exact mechanism is not fully understood. The case illustrates the added value of a multimodality imaging approach in patients presenting with hyperammonemia-induced encephalopathy.

Pancreatic Neuroendocrine Neoplasm Invading the Entire Main Pancreatic Duct Diagnosed by a Preoperative Endoscopic Biopsy

A 78-year-old man was referred to our hospital for a detailed examination of a pancreatic tumor that filled the main pancreatic duct (MPD). The histological diagnosis of the endoscopic biopsy specimen was neuroendocrine tumor (NET) G3. The patient subsequently underwent total pancreatectomy. The histological diagnosis of the surgical specimen was also NET G3. This is the first report of a NET that occupied the MPD and was diagnosed by a preoperative endoscopic biopsy through the papilla of Vater. This case is a good example of a histopathological diagnostic method for pancreatic tumors invading the entire MPD.

Pancreatic neuroendocrine tumor featuring growth into the main pancreatic duct and tumor thrombus within the splenic vein: a case report

A 48-year-old woman was admitted to our hospital because of upper abdominal pain. Computer tomography showed an enhancing mass in the pancreatic body, dilation of the main pancreatic duct (MPD) and a filling defect within the splenic vein. On the basis of the preoperative diagnosis of pancreatic body cancer, distal pancreatectomy was scheduled. The pancreas was divided along the left edge of the gastroduodenal artery; however, frozen pathological examination of the pancreatic stump was tumor positive, and therefore a total pancreatectomy was performed. The lesion was a white expansive nodular mass that had spread into the MPD and protruded into the splenic vein. A pathological diagnosis of non-functioning neuroendocrine tumor (NET) was made. In general, imaging findings of disruption of the MPD and tumor vein thrombus are characteristics of pancreatic ductal adenocarcinoma, but are uncommon in NET. However, NET should be included in the differential diagnosis for such patients.

Imaging presentation of pancreatic neuroendocrine neoplasms

Abstract

Pancreatic neuroendocrine neoplasms (P-NENs) are the second most common solid pancreatic neoplasms. P-NENs have a wide range of imaging features presentations and they can be detected with typical and atypical imaging presentations. Typical and atypical appearances can be explained by pathologic correlations. P-NENs are generally hypervascular lesions, showing a typical enhancement behavior after contrast media injection during imaging methods, but they could also have different imaging features, creating some difficulty in differential diagnosis. For this reason, radiologists should be aware of different imaging presentations of these neoplasms. Radiological evaluation has a critical role in P-NENs identification, characterization, and staging of these neoplasms, especially in those cases in which surgery is the treatment of choice. The present paper shows, indicating the underlying pathologic correlations, typical and atypical presentations of NENs.

Key Points

• P-NENs have a wide range of imaging features presentations, typical and atypical.

• Pathology could help in better understanding the typical P-NENs appearance at imaging.

• P-NENs are generally hypervascular lesions.

• Radiological evaluation has a critical role in P-NENs identification and management.

• Radiologists should know every type of different imaging presentation of P-NENs to better diagnose these kinds of lesions.

A resected case of intraductal tubulopapillary neoplasm of the pancreas: report of a case

The patient was a 61-year-old male who was referred to our hospital after dilatation of the main pancreatic duct was detected by screening ultrasonography. Computed tomography revealed a protruding lesion measuring 15 mm in diameter within the main pancreatic duct in the head of the pancreas, and magnetic resonance cholangiopancreatography revealed interruption of the duct at the tumor site. We performed pancreaticoduodenectomy under a suspected diagnosis of invasive ductal carcinoma. Gross examination of the resected specimen showed that the tumor invaginated into the main pancreatic duct, and no mucin was found. Histological examination revealed proliferation of high-grade dysplastic cells in a tubulopapillary growth pattern. Immunohistochemically, cytokeratin 7 expression was detected, but not trypsin expression. Based on these morphological features, we diagnosed the tumor as intraductal tubulopapillary neoplasm (ITPN). We report the case with bibliographic consideration, together with a review of intraductal neoplasms of the pancreas encountered at our institution.

A case of undifferentiated carcinoma of the pancreas mimicking main-duct intraductal papillary mucinous neoplasm (IPMN)

We report here a rare case of undifferentiated carcinoma of the pancreas mimicking main-duct intraductal papillary mucinous neoplasm. In an 80-year-old woman, an approximately 8-mm papillary mass was incidentally detected at the downstream edge of a dilatated main pancreatic duct lumen on CT and MRI. Main pancreatic duct dilatation in the pancreatic body and tail and parenchymal atrophy were observed in the upstream of the mass. Histopathologically, the tumor protruded into the downstream edge of the dilatated main pancreatic duct lumen in the pancreatic body. The tumor cells had highly atypical nuclei and abundant polymorphic structures, and showed positive staining for granulocyte colony-stimulating factor, which led to the diagnosis of undifferentiated carcinoma. A total of 13 cases of undifferentiated carcinoma with intraductal tumor growth have been reported to date. The case report by Bergmann et al. has been the smallest in histopathological specimen, and the present case is the smallest in size detected by radiological images. Since early undifferentiated carcinoma of the pancreas can resemble those of main-duct intraductal papillary mucinous neoplasm in cross-sectional images, we have to consider undifferentiated carcinoma in the differential diagnosis of the solitary and papillary mass with low contrast enhancement in early phase in the main pancreatic duct.

Histopathology of gastrointestinal neuroendocrine neoplasms

Gastrointestinal neuroendocrine neoplasms (GI-NENs) arise from neuroendocrine cells distributed mainly in the mucosa and submucosa of the gastrointestinal tract. In 2010, the World Health Organization (WHO) classification of NENs of the digestive system was changed, categorizing these tumors as grade 1 neuroendocrine tumor (NET), grade-2NET, neuroendocrine carcinoma (large- or small-cell type), or mixed adenoneuroendocrine carcinoma (MANEC). Such a classification is based on the Ki-67 index and mitotic count in histological material. For the accurate pathological diagnosis and grading of NENs, it is important to clearly recognize the characteristic histological features of GI-NENs and to understand the correct method of counting Ki-67 and mitoses. In this review, we focus on the histopathological features of GI-NENs, particularly regarding biopsy and cytological diagnoses, neuroendocrine markers, genetic and molecular features, and the evaluation of the Ki-67 index and mitotic count. In addition, we will address the histological features of GI-NEN in specific organs.