Incidental T1a Gallbladder Cancer with Signet Ring Cell Carcinoma Following Laparoscopic Cholecystectomy: A Case Report.

Introduction: Signet ring cell carcinoma (SRC) of the gallbladder is a rare type of gallbladder cancer. We report a case of SRC of the gallbladder that was characterized by the diffuse presence of SRC on the gallbladder mucosa and diagnosed after cholecystectomy.

Case presentation: A 40-year-old man was referred to our department with upper abdominal pain and vomiting. Based on the findings of blood tests, computed tomography, and magnetic resonance imaging, acute cholecystitis was suspected, and emergency laparoscopic cholecystectomy was performed. Intraoperative findings showed mild inflammation. Although the tumor remained within the mucosa, tumor cell infiltration was suspected at the edge of cystic duct pathologically. Although additional endoscopic ultrasound and endoscopic retrograde cholangiography showed that horizontal extension into the residual cholecystic duct was suspected, there was no evidence of invasion into the common bile duct, lymph node metastasis, or distant metastasis. One and a half months after cholecystectomy, the patient underwent extrahepatic bile duct resection, lymph node dissection, and bile duct jejunal anastomosis. The postoperative course was uneventful, and the patient was discharged on the 10th postoperative day. Postoperative pathological analysis showed no obvious residual tumor tissue in the common bile duct or choledochal duct margins, and no metastasis in the submitted lymph nodes. Based on the above, a diagnosis of pT1aN0M0, pStage IA SRC was made. As no lymph node metastasis was observed, it was decided to follow up the patient without initiating postoperative chemotherapy, and the patient has been recurrence-free for 12 months after surgery.

Conclusions: We describe an incidentally discovered case of intramucosal SRC diffusely spreading throughout the gallbladder after cholecystectomy for acute cholecystitis.