Loculated fluid collections in hepatic fissures and recesses: CT appearance and potential pitfalls.

The peritoneum invaginates into the liver parenchyma normally, as a normal anatomic variation, or pathologically and then fissures and furrows are formed. There are four normal fissures: fissures for the ligamentum teres, ligamentum venosum, and gallbladder and the transverse fissure. Fissures caused by normal anatomic variations include accessory fissures and furrows created by diaphragmatic indentation. Pathologic fissures occur secondary to traumatic or iatrogenic causes or as a result of liver cirrhosis. When ascites, hemoperitoneum, or infected ascites is loculated in the fissures or recesses, it may be mistaken for a liver cyst, intrahepatic hematoma, or liver abscess. When peritoneally disseminated tumor cells are implanted into these spaces, they may mimic intrahepatic focal lesions. Because the clinical consequences for these entities are very different, exact localization of the lesions may be crucial in the diagnosis and management of the lesions. Complete understanding of the liver surface anatomy and awareness of these situations may prevent a misdiagnosis of a focal intrahepatic abnormality.