A New Preoperative Scoring System for Predicting Aggressiveness of Non-Functioning Pancreatic Neuroendocrine Neoplasms

A nomogram to preoperatively predict the aggressiveness of non-functional pancreatic neuroendocrine tumors based on CT features

OBJECTIVES

To develop a nomogram to predict the aggressiveness of non-functional pancreatic neuroendocrine tumors (NF-pNETs) based on preoperative computed tomography (CT) features.

METHODS

This study included 176 patients undergoing radical resection for NF-pNETs. These patients were randomly divided into the training (n = 123) and validation sets (n = 53). A nomogram was developed based on preoperative predictors of aggressiveness of the NF-pNETs which were identified by univariable and multivariable logistic regression analysis. The aggressiveness of NF-pNETs was defined as a composite measure including G3 grading, N+, distant metastases, and/ or disease recurrence.

RESULTS

Altogether, the number of patients with highly aggressive NF-pNETs was 37 (30.08 %) and 15 (28.30 %) in the training and validation sets, respectively. Multivariable logistic regression analysis identified that tumor size, biliopancreatic duct dilatation, lymphadenopathy, and enhancement pattern were preoperative predictors of aggressiveness. Those variables were used to develop a nomogram with good concordance statistics of 0.89 and 0.86 for predicting aggressiveness in the training and validation sets, respectively. With a nomogram score of 59, patients with NF-pNETs were divided into low-aggressive and high-aggressive groups. The high-aggressive group had decreased overall survival (OS) and disease-free survival (DFS). Moreover, the nomogram showed good performance in predicting OS and DFS at 3, 5, and 10 years.

CONCLUSION

The nomogram integrating CT features helped preoperatively predict the aggressiveness of NF-pNETs and could potentially facilitate clinical decision-making.

The Ki67 index evaluation of pancreatic neuroendocrine tumors using 3D immunohistochemistry in small tissue specimens

BACKGROUND

/Objectives: This study aimed to evaluate the usefulness of three-dimensional (3D) immunohistochemistry for the Ki67 index of small tissue specimens of pancreatic neuroendocrine tumor (PanNET).

METHODS

Clinicopathological materials from 17 patients with PanNET who underwent surgical resection at Jichi Medical University Hospital were analyzed. We compared the Ki67 index of endoscopic ultrasonography-fine-needle aspiration biopsy (EUS-FNAB) specimens, surgical specimens, and small tissue specimens hollowed from paraffin blocks of surgical specimens that were substituted for EUS-FNAB specimens ("sub-FNAB"). The sub-FNAB specimens were optically cleared using LUCID (IlLUmination of Cleared organs to IDentify target molecules) and analyzed using 3D immunohistochemistry.

RESULTS

The median Ki67 index in FNAB, sub-FNAB, and surgical specimens with conventional immunohistochemistry were 1.2% (0.7-5.0), 2.0% (0.5-14.6), and 5.4% (1.0-19.4), respectively. The median Ki67 index in sub-FNAB specimens with tissue clearing was calculated separately using the total number of cells on multiple images ("multiple slice"), with the image of the fewest positive cells ("coldspot"), and with the image of most positive cells ("hotspot"), which were 2.7% (0.2-8.2), 0.8% (0-4.8), and 5.5% (2.3-12.4), respectively. PanNET grade evaluated for the hotspot of the surgical specimens was significantly more consistent with those of the hotspot than multiple images of sub-FNAB specimens (16/17 vs. 10/17, p = 0.015). Hotspot evaluation using 3D immunohistochemistry of the sub-FNAB specimens showed agreement with the assessment of the surgical specimens (Kappa coefficient: 0.82).

CONCLUSIONS

Tissue clearing and 3D immunohistochemistry for the Ki67 index can potentially improve the preoperative evaluation of EUS-FNAB specimens of PanNET in routine clinical practice.

Serotonin-positive neuroendocrine neoplasm with pancreatic ductal dilation in which cytological immunostaining contributed to the diagnosis

A 52-year-old man was transported via an ambulance because of syncope and the passage of tarry stools, which had been noted the previous day. He was diagnosed with upper gastrointestinal bleeding from a gastric ulcer and underwent endoscopic hemostasis. Prior to endoscopy, abdominal computerized tomography performed for gastrointestinal bleeding revealed pancreatic duct dilation. After discharge, abdominal imaging revealed a strongly enhancing tumor (5 mm) with caudal pancreatic duct dilation. Endoscopic retrograde pancreatography revealed that the main pancreatic duct was interrupted at the body. Pancreatic juice cytology was class III, and additional immunostaining were positive for chromogranin A, synaptophysin, and serotonin, suggesting a pancreatic neuroendocrine neoplasm (NEN). Distal pancreatectomy was performed and a yellowish-white solid lesion was found in the pancreatic duct. Pathological examination revealed narrowing of the pancreatic duct, extensive stromal fibrosis, and proliferation of tumor cells with small round nuclei and eosinophilic vesicles. Furthermore, the immunostaining findings of the resected specimen corresponded with those of the cytology. A diagnosis of NEN G1 (WHO classification) with Ki-67 index < 1% was made. Imaging of the pancreatic duct tend to be normal or show no involvement of the duct in pancreatic neuroendocrine neoplasms; however, there have been a few reports of stenosis due to fibrosis around the pancreatic duct. Serotonin positivity was previously documented to be significantly higher in patients with fibrosis. In lesions with pancreatic ductal stenosis, the addition of immunostaining to pancreatic juice cytology was thought to be useful in differentiating pancreatic cancer from pNEN.