Delayed Diagnosis of Mirizzi Syndrome

Area of Science:

• Gastroenterology and Hepatology
• Surgical Pathology
• Diagnostic Imaging

Background:

• Biliary obstruction is a common clinical presentation with diverse etiologies, encompassing both malignant and benign pathologies.
• Mirizzi syndrome, characterized by external compression of the common hepatic duct by an impacted gallstone in the cystic duct or gallbladder neck, presents a unique subset of biliary obstruction.
• The syndrome's rarity and variable imaging findings can lead to diagnostic ambiguity, often mimicking other intra-abdominal pathologies.

Approach:

• This report details a unique case of biliary obstruction attributed to Mirizzi syndrome.
• The initial diagnostic workup was complicated by atypical imaging features of the gallstone, leading to a differential diagnosis that included malignancy and hepatic pseudoaneurysm.
• The definitive diagnosis was established following the patient's presentation with gallstone ileus, a rare complication.

Key Points:

• External compression of the hepatic duct by a gallstone (Mirizzi syndrome) is an uncommon cause of biliary obstruction.
• Unusual imaging characteristics of the gallstone can mimic malignant masses or vascular abnormalities, posing significant diagnostic challenges.
• The development of gallstone ileus served as a critical diagnostic clue, facilitating the correct identification of Mirizzi syndrome.

Conclusions:

• Mirizzi syndrome, though rare, must be considered in the differential diagnosis of biliary obstruction, especially when imaging findings are atypical.
• A high index of suspicion and careful correlation of clinical, imaging, and eventual pathological findings are crucial for accurate diagnosis.
• Gallstone ileus, while a complication, can sometimes be the key to unmasking an underlying Mirizzi syndrome.