Intracholecystic papillary neoplasm associated with invasive carcinoma of the remnant gallbladder after subtotal cholecystectomy: a case report

BACKGROUND: Intracholecystic papillary neoplasm (ICPN) of the gallbladder is a rare tumor and a relatively new concept. Therefore, the natural history and imaging characteristics of ICPN have not yet been fully documented. Moreover, cases who underwent curative resection for remnant gallbladder cancer, including ICPN with associated invasive carcinoma, have been rarely reported. We report a resected case of ICPN of the remnant gallbladder with associated invasive carcinoma for which we could observe a temporal change in imaging findings until malignant transformation. CASE PRESENTATION: A 79-year-old female patient with a surgical history of subtotal cholecystectomy for acute cholecystitis was an ambulatory patient of our institution because of postoperative surveillance for colon cancer. Ultrasonography and computed tomography incidentally detected a small nodule in the cystic remnant gallbladder. The nodule had increased in size 3 months later; thus, additional investigations were performed. Magnetic resonance imaging revealed a 10-mm enhanced nodule without evidence of extraluminal invasion. Diffusion-weighted magnetic resonance imaging revealed restricted diffusion of the lesion, and positron emission tomography revealed marked accumulation in the lesion. The lesion was diagnosed as suspicious for a malignant remnant gallbladder tumor. Therefore, remnant cholecystectomy with gallbladder bed resection was performed. Because preoperative endoscopic retrograde cholangiography revealed a relatively long intact cystic duct, extrahepatic bile duct resection was planned to be omitted. Intraoperatively, the hepatic and duodenal side bile duct where the cystic duct diverged was taped. Using these tapes, which permitted pulling the bile duct, the cystic duct located behind the bile duct could be safely exposed. The lesion was pathologically diagnosed as biliary morphologic ICPN with associated invasive carcinoma. CONCLUSIONS: Because remnant cholecystectomy is an uncommon procedure and technically difficult, accurate preoperative investigation and surgical planning are important to prevent bile duct injury and omit extrahepatic bile duct resection. In the present case, intracystic change could be detected incidentally at an early stage because of previous remnant gallbladder producing (reconstituting) subtotal cholecystectomy and surveillance for other disease. This case suggests the existence of ICPN that can progress to invasive carcinoma during a short period.