Mucinous Adenocarcinoma of Gallbladder Presenting As Acute Calculous Cholecystitis.

Mucinous adenocarcinoma (MAC) is a rare type of gallbladder cancer accounting for less than 5% of the reported cases. It is characterized by mucin deposition involving more than 50% of the tumor volume. It is a distinct subtype of gallbladder cancer and associated with poor prognosis. Accurate preoperative diagnosis is difficult. Most of the cases are diagnosed incidentally during the histopathological examination of the resected gallbladder. We report the case of a 75-year-old man who presented with right upper abdominal pain, fever, and vomiting for 15 days. Abdominal ultrasound revealed acute calculous cholecystitis for which he underwent laparoscopic cholecystectomy. Histological examination of the gallbladder found ulcerated gallbladder mucosa lined with dysplastic epithelium. The tumor was mainly composed of dysplastic glands floating in the pools of mucin with invasion of the perivascular connective tissue suggestive of MAC. This case highlights the importance of histological examination of gallbladder after routine cholecystectomy.