Islet cell tumours

A MODEL TO PREDICT DIAGNOSIS OF PANCREATIC NEUROENDOCRINE TUMORS BASED ON EUS IMAGING FEATURES

Background

This study aimed to determine predictive clinical and endoscopic ultrasound (EUS) features for pancreatic neuroendocrine tumor (PNET) diagnosis, utilizing EUS-guided tissue acquisition.

Methods

A prospective study from 2018-2022 included patients with pancreatic masses undergoing EUS with elastography. Univariate binomial logistic regression followed by multiple logistic regression with significant predictors was employed. A forward selection algorithm identified optimal models based on predictor numbers. Variables encompassed EUS tumor characteristics (e.g., location, size, margins, echogenicity, vascularity on Doppler, main pancreatic duct dilation, elastography appearance, vascular invasion, and hypoechoic rim), alongside demographic and risk factors (smoking, alcohol, diabetes).

Results

We evaluated 165 patients (24 PNETs). EUS features significantly linked with PNET diagnosis were well-defined margins (79% vs. 26%, p < 0.001), blue elastography appearance (46% vs. 9.9%, p < 0.001), vascularization (67% vs. 25%, p < 0.001), hypoechoic rim (46% vs. 10%, p < 0.001). The top-performing model, with 89.1% accuracy, included two predictors: a homogeneous lesion (OR, 95% CI) and a hypoechoic rim (OR, 95% CI).

Conclusions

EUS appearance can differentiate PNETs from non-PNETs, with the hypoechoic rim being an independent predictor of PNET diagnosis. The most effective predictive model for PNETs combined the homogeneous lesion and presence of the hypoechoic rim.

Metastatic pancreatic polypeptide-secreting islet cell tumor in a dog

A 14-year-old female spayed Golden Retriever was presented to the University of Florida's Veterinary Medical Center with history of lymphoplasmacytic gastroenteritis, intermittent vomiting, watery diarrhea, and weight loss for over a year. CBC, biochemical profile, and urinalysis were within reference intervals. Abdominal ultrasonographic examination revealed mesenteric and jejunal lymphadenopathy and hyperechoic hepatic nodules. Cytologic examination of the enlarged lymph nodes revealed loosely cohesive cells with moderate nuclear pleomorphism and rare punctate eosinophilic cytoplasmic granules. The cytologic interpretation was metastatic neuroendocrine neoplasia. On surgical exploration, a mass was detected in the right lobe of the pancreas. Histologic evaluation determined the mass to be an islet cell tumor. Approximately 98% of cells were positive by immunolabeling for pancreatic polypeptide (PP), and only rare cells were positive for insulin or somatostatin. All cells were negative for glucagon, gastrin, vasoactive intestinal polypeptide, protein gene product 9.5, synaptophysin, and chromogranins A and B. Pancreatic tumors that primarily produce PP are rare in dogs, and this is the first report of both the cytologic and histologic features of an islet cell tumor predominantly secreting PP. Clinical signs for these tumors are typically absent or nonspecific; signs may include watery diarrhea, as noted in this dog, although the diarrhea may have resulted from lymphoplasmacytic gastroenteritis. Additional case studies are needed to further characterize the cytomorphologic features and clinical presentation of PP-secreting islet cell tumor, or polypeptidoma, in dogs.

Dual-phase multidetector thin-section CT in detecting duodenal gastrinoma

Preoperative localization of gastrinomas, especially of extrapancreatic origin, remains a challenge to the radiologist. Most patients with extrapancreatic gastrinomas undergo surgery without preoperative identification of the primary tumor. The appropriate imaging modality to localize gastrinomas is under continuing debate. We report a case of a duodenal gastrinoma with regional lymph node metastases that presented with Zollinger-Ellison syndrome. The small primary tumor was detected noninvasively by dual-phase multidetector thin-section computed tomography with adequate bowel distention and confirmed by endoscopy and histopathologic examination. The case illustrates that appropriate computed tomographic technique and scanning protocol are crucial for success in localizing extrapancreatic gastrinoma.