[Amputation neuroma with a difficult differential diagnosis from perihilar cholangiocarcinoma:a case report].

Biliary amputation neuroma is a rare benign tumor that develops due to the peribiliary dissection of nerve fibers during cholecystectomy, a common bile duct surgery, or lymph node dissection performed in gastric cancer surgery. We report a case of amputation neuroma that presented a challenging differential diagnosis from perihilar cholangiocarcinoma. A 64-year-old man, who had undergone open cholecystectomy 30 years ago, was incidentally found to have a bile duct tumor during computed tomography (CT) following surgery for renal cell carcinoma. He had no specific symptoms, and blood test results showed only a slight elevation in alkaline phosphatase levels. Contrast-enhanced CT revealed a 10-mm solid tumor with contrast effect in the common bile duct. On cholangiography, the tumor appeared as a protruding lesion with a smooth surface unilaterally. Given the atypical findings suggestive of cholangiocarcinoma, three bile duct biopsies were performed. Pathological examination did not rule out adenocarcinoma. The patient opted for surgery;however, an intraoperative rapid histological examination confirmed a benign disease, thereby avoiding extensive surgery. Consequently, a minimally invasive bile duct resection was performed. Postoperative histopathological examination revealed the tumor to be an amputation neuroma. Biliary amputation neuromas are characterized as unilateral protruding lesions with contrast effect or benign strictures. If such findings are observed in a patient with a history of surgery around the bile duct, the possibility of an amputation neuroma should be considered. However, completely ruling out malignancy preoperatively, even when suspecting amputation neuroma, can be challenging;therefore, considering surgery to achieve a definitive diagnosis is reasonable. During surgery, a rapid intraoperative histological examination is useful to avoid extensive procedures. In conclusion, diagnosing an amputation neuroma before surgery can be difficult, as it can mimic malignant tumors such as bile duct cancers. In this case, although a preoperative diagnosis of amputation neuroma was not feasible, performing a rapid intraoperative pathological examination helped avoid extensive surgery.

A case of poorly differentiated mucinous carcinoma of the gallbladder that exhibited a peculiar morphology.

A 65-year-old female presented with an elevated lesion that was identified in the gallbladder fundus via abdominal ultrasound during a medical checkup. The tumor was a pedunculated lesion, measuring 30mm in diameter, that exhibited a blood flow pattern with gradual dense staining throughout the equilibrium phase on the abdominal contrast computed tomography and a high signal intensity on T2-weighted magnetic resonance imaging. Histopathological findings revealed the proliferation of poorly differentiated adenocarcinoma, including signet ring cells, throughout the tumor along with the formation of a mucous lake. The patient was consequently diagnosed with poorly differentiated mucinous carcinoma of the gallbladder.

Portal vein stenting blocked the inflow tract and completely resolved bile duct varices, formed by cavernous transformation of the portal vein.

There is no established treatment for bleeding bile duct varices (BDVs). We report the first case of portal vein (PV) stenting completely eradicating bleeding BDVs. A 70-year-old male with malignant lymphoma developed BDVs due to PV obstruction, which had caused compression and stricture of the distal bile duct. Endoscopic retrograde cholangiography was performed to evaluate the stricture and bleeding from the ruptured BDV was observed. Endoscopic hemostasis was difficult, requiring reopening of the extra-hepatic PV and reducing the blood flow to the BDVs for hemostasis. Therefore, PV stenting was performed. During the procedure, portal angiography confirmed an inflow tract to the BDVs. Therefore, covered stents were placed in the PV and adjusted to block the inflow tract to the BDVs at the distal end. After stenting, the BDVs were successfully blocked and all PV blood flowed through the stent placed in the extra-hepatic PV. Two weeks after stenting, the BDVs had disappeared completely and the bleeding has not recurred for months. We experienced a case in which PV stenting not only reopened an obstructed PV but also successfully occluded the inflow tract. This case demonstrates the potential of PV stenting for the treatment of hemorrhagic BDVs.

Machine learning-based model for prediction and feature analysis of recurrence in pancreatic neuroendocrine tumors G1/G2.

BACKGROUND: Pancreatic neuroendocrine neoplasms (PanNENs) are a heterogeneous group of tumors. Although the prognosis of resected PanNENs is generally considered to be good, a relatively high recurrence rate has been reported. Given the scarcity of large-scale reports about PanNEN recurrence due to their rarity, we aimed to identify the predictors for recurrence in patients with resected PanNENs to improve prognosis. METHODS: We established a multicenter database of 573 patients with PanNENs, who underwent resection between January 1987 and July 2020 at 22 Japanese centers, mainly in the Kyushu region. We evaluated the clinical characteristics of 371 patients with localized non-functioning pancreatic neuroendocrine tumors (G1/G2). We also constructed a machine learning-based prediction model to analyze the important features to determine recurrence. RESULTS: Fifty-two patients experienced recurrence (14.0%) during the follow-up period, with the median time of recurrence being 33.7 months. The random survival forest (RSF) model showed better predictive performance than the Cox proportional hazards regression model in terms of the Harrell's C-index (0.841 vs. 0.820). The Ki-67 index, residual tumor, WHO grade, tumor size, and lymph node metastasis were the top five predictors in the RSF model; tumor size above 20 mm was the watershed with increased recurrence probability, whereas the 5-year disease-free survival rate decreased linearly as the Ki-67 index increased. CONCLUSIONS: Our study revealed the characteristics of resected PanNENs in real-world clinical practice. Machine learning techniques can be powerful analytical tools that provide new insights into the relationship between the Ki-67 index or tumor size and recurrence.