A large pseudolesion in the left lobe of the liver caused by inferior vena caval obstruction secondary to metastatic retroperitoneal lymphadenopathy

Lesion or Pseudolesion? A Comprehensive Description of Perfusion-Based Liver Alterations on Contrast-Enhanced Computed Tomography and Literature Review

ABSTRACT

Pseudolesions on contrast-enhanced computed tomography represent a diagnostic challenge for radiologists because they could be difficult to distinguish from true space-occupying lesions. This article aims to provide a detailed overview of these entities based on radiological criteria (hyperattenuation or hypoattenuation, localization, morphology), as well as a brief review of the hepatic vascular anatomy and pathophysiological process. Relevant examples from hospital case series are reported as helpful hints to assist radiologists in recognizing and correctly diagnosing these abnormalities.

Benign Neoplasms, Mass-Like Infections, and Pseudotumors That Mimic Hepatic Malignancy at MRI

A variety of conditions may mimic hepatic malignancy at MRI. These include benign hepatic tumors and tumor-like entities such as focal nodular hyperplasia-like lesions, hepatocellular adenoma, hepatic infections, inflammatory pseudotumor, vascular entities, and in the cirrhotic liver, confluent fibrosis, and hypertrophic pseudomass. These conditions demonstrate MRI features that overlap with hepatic malignancy, and can be challenging for radiologists to diagnose accurately. In this review we discuss the MRI manifestations of various conditions that mimic hepatic malignancy, and highlight features that may allow distinction from malignancy. Level of Evidence 5 Technical Efficacy Stage 3.

Treatment of a non-typical hepatic pseudolesion complicated by greatly elevated alpha fetoprotein: case report and literature review

Background

Hepatic pseudolesions detected by helical computed tomography (CT) are not rare, but it is difficult to make a final diagnosis when the hepatic lesion is complicated by the presence of greatly elevated alpha fetoprotein (AFP). Clinical treatment of non-typical hepatic pseudolesions complicated by greatly elevated AFP should confirm the diagnosis and minimize trauma.

Case presentation

Non-invasive procedures including ultrasonography, CT, and micro-invasive digital subtraction angiography could not safely differentiate this lesion from a malignant focus when it was complicated by greatly elevated AFP. Laparoscopic hepatectomy was performed, and pathological analysis showed chronic hepatitis, nodular regenerative hyperplasia, focal nodular hyperplasia of the liver, and mild vascular malformation. The tissue was HbsAg(−), HbcAg(−), and AFP(+).

Conclusion

Heightened awareness of hepatic pseudolesion complicated by primarily elevated AFP will help physicians avoid unnecessary invasive procedures. Hepatic biopsy is inevitable because of greatly elevated AFP. For suspected hepatic pseudolesion with elevated AFP, needle-core biopsy and follow-up surveillance instead of hepatectomy are recommended to find the source of AFP and make a final diagnosis of pseudolesion.

Pitfalls in the imaging diagnosis of hepatocellular nodules in the cirrhotic and noncirrhotic liver

Contrast-enhanced CT and MR are the most commonly used modalities for objective evaluation of hepatocellular nodules. Various types of pseudolesions as seen on CT or MR have been reported, which are attributable to either focal alteration in hemodynamics or parenchymal metabolism, or to both. Pseudolesions specifically seen in cirrhotic liver include arterio-portal shunt, regenerating or hyperplastic nodules, and confluent fibrosis. In noncirrhotic liver, transient focal compression to the liver, third inflow other than normal hepatic arterial and portal venous flow, and vessel compromise are the causes of pseudolesions. To understand the characteristic features of these pseudolesions, and their underlying mechanism as well, is important for proper diagnosis of true hepatocellular lesions.

Unusual hemodynamics and pseudolesions of the noncirrhotic liver at CT

Recognition of pseudolesions of the liver at computed tomography (CT) is important because of their close resemblance to primary liver cancers or metastases. Two types of pseudolesion in the noncirrhotic liver include that due to transient extrinsic compression, typically caused by ribs or the diaphragm, and that due to a "third inflow" of blood from other than the usual hepatic arterial and portal venous sources: the cholecystic, parabiliary, or epigastric-paraumbilical venous system. Although the location of both types of pseudolesion are characteristic, their appearances at CT during arterial portography and CT during selective angiography vary from nonenhanced low-attenuation areas to well-enhanced high-attenuation areas, depending on the amount and timing of the inflow and presence or absence of focal metabolic alteration of the hepatocytes. Radiologists need to understand the underlying mechanism of these pseudolesions to better recognize the wide range of their appearances at CT.