Dropped Gallstone Mimicking Retroperitoneal Tumor 5 Years After Laparoscopic Cholecystectomy Posing a Diagnostic Challenge.

Laparoscopic cholecystectomy is the standard treatment for cholecystitis. The major complications associated with laparoscopic cholecystectomy include bleeding, abscess formation, biliary injury with bile leakage, and bowel injury. Gallbladder perforation and subsequent stone spillage are not uncommon in laparoscopic cholecystectomy. The majority of these spilled stones remain clinically silent. But sometimes they can cause abscesses and make diagnosis challenging especially when it occurs years after the procedure and when the abscess form in uncommon sites. A 66-year-old female with a history of laparoscopic cholecystectomy presented with aggravating abdominal pain in the right upper quadrant (RUQ). The CT abdomen revealed a mass in the retroperitoneum behind the hepatic flexure. Upon further examination, follow-up CT scans, and biopsy repeatedly failed to exclude malignancy, so it was suggested that the patient undergo surgical removal of the mass. The pathological analysis of the excised mass revealed that it was a dropped gallstone from the procedure that triggered an inflammatory reaction. Dropped gallstones should be considered as a differential diagnosis in a patient with a history of laparoscopic cholecystectomy presenting with an abdominal or retroperitoneal abscess, as a failure of early recognition puts the patient at risk of undergoing unnecessary and invasive procedures.