Liver masses: a clinical, radiologic, and pathologic perspective

Abstract

Liver masses present a relatively common clinical dilemma, particularly with the increasing use of various imaging modalities in the diagnosis of abdominal and other symptoms. The accurate and reliable determination of the nature of the liver mass is critical, not only to reassure individuals with benign lesions but also, and perhaps more importantly, to ensure that malignant lesions are diagnosed correctly. This avoids the devastating consequences of missed diagnosis and the delayed treatment of malignancy or the unnecessary treatment of benign lesions. With appropriate interpretation of the clinical history and physical examination, and the judicious use of laboratory and imaging studies, the majority of liver masses can be characterized noninvasively. Accurate characterization of liver masses by cross-sectional imaging is particularly dependent on an understanding of the unique phasic vascular perfusion of the liver and the characteristic behaviors of different lesions during multiphasic contrast imaging. When noninvasive characterization is indeterminate, a liver biopsy may be necessary for definitive diagnosis. Standard histologic examination usually is complemented by immunohistochemical analysis of protein biomarkers. Accurate diagnosis allows the appropriate selection of optimal management, which is frequently reassurance or intermittent follow-up evaluations for benign masses. For malignant lesions or those at risk of malignant transformation, management depends on the tumor staging, the functional status of the uninvolved liver, and technical surgical considerations. Unresectable metastatic masses require oncologic consultation and therapy. The efficient characterization and management of liver masses therefore requires a multidisciplinary collaboration between the gastroenterologist/hepatologist, radiologist, pathologist, hepatobiliary or transplant surgeon, and medical oncologist.

Keywords: Cholangiocarcinoma; Focal Nodular Hyperplasia; Hepatic Adenoma; Hepatic Hemangioma; Hepatocellular Carcinoma; Liver Imaging.

Figure 1

Microscopic section of cavernous hemangioma (hematoxylin and eosin stain × 100) showing multiple vascular spaces lined by a single layer of benign endothelial cells (arrow).

Figure 2

MRI of a cavernous hemangioma of the liver. The hemangioma (arrow) shows typical bright signal on T2-weighted image, hypointensity on T1-weighted image and peripheral nodular enhancement in the arterial phase with centripetal filling in the portal venous phase and near complete filling in the delayed phase. GB - gall bladder.

Figure 3

Ultrasound (left panel) and contrast enhanced CT (right panel) of liver showing a simple cyst (*).

Figure 4

Focal nodular hyperplasia (arrow) seen as isointense to hypointense liver parenchyma on T2 and T1-weighted images with a central T2 hyperintense scar. During the arterial phase there is intense homogeneous enhancement of the mass which becomes isointense in portal venous and delayed phases. Positive uptake is seen in the hepatocyte phase which is characteristic. The gross picture shows a well-circumscribed lesion exhibiting the characteristic central scar (arrow). The microscopic section (hematoxylin and eosin stain × 40) shows a scar in the center (long arrow) with a few thick walled vessels subdividing the lesion into smaller nodules. There is also steatosis within the hepatocytes (short arrow).

Figure 5

Hepatic adenoma (arrow) in the left lobe in a patient with hepatic adenomatosis. The mass is slightly heterogeneous and hyperintense to liver on T2 weighted image and iso-to hypointense on the T1 weighted image. It demonstrated arterial phase enhancement (not shown) but is nearly isointense in the portal venous phase. The gross picture shows three well-demarcated lesions within the liver (white arrows). The microscopic section (hematoxylin and eosin stain × 200) shows sheets of benign hepatocytes with a naked artery (long arrow). There is also some steatosis (short arrow) within the tumor.

Figure 6

Hepatic adenoma (arrow) in the right lobe of the liver. The adenoma is hyperintense to liver on T2 weighted image and isointense on the T1 weighted image. It is hyper-enhancing in the arterial phase but nearly isointense in the portal venous phase and does not take up Eovist in the hepatocyte phase. An adjacent simple cyst is marked on the T2 weighted image (*).

Figure 7

Examples of focal fat sparing (upper panels) and focal fat change (lower panels) adjacent to the falciform ligament and the peri-portal region.

Figure 8

Klebsiella liver abscess. Contrast-enhanced CT showing a large multi-loculated hypodense rim-enhancing mass in the right lobe of the liver consistent with a liver abscess. The patient presented with fever, abdominal pain and raised serum liver enzymes.

Figure 9

Hepatocellular carcinoma on CT. The mass appears heterogeneous due to the presence of intra-tumoral fat confirmed at histology. The mass shows arterial phase enhancement with portal venous and delayed phase washout with a thin pseudocapsule (black arrow heads). The gross picture shows a large mass within the right lobe of the liver. A separate small satellite lesion is also seen (white arrow). The microscopic section (hematoxylin and eosin stain × 400) shows hepatocellular carcinoma exhibiting a trabecular architecture with thickened hepatic cords and rare mitosis (black arrow).

Figure 10

Intrahepatic cholangiocarcinoma. The mass is iso- to hyper-intense on T2-weighted image, bright on the diffusion weighted image and hypointense on T1-weighted image. There is peripheral thin rim enhancement in the arterial phase which persists into the portal venous phase and a thick rim-like enhancement in the delayed phase without washout. Note the enhancement of the surrounding liver in arterial phase due to perfusional change caused by the tumor. The tumor shows FDG uptake on the PET scan. The gross picture shows a white lesion (white arrow). The microscopic section (hematoxylin and eosin stain × 400) shows an adenocarcinoma composed of neoplastic glandular proliferation with some areas showing lumen formation (black arrow).