With triple-phase helical CT, the sensitivity was 90% or higher, but these data have not been confirmed with autopsy studies.However, MRI has the advantage of delivering high-resolution images of the liver without ionizing radiation. HCC appears as a high-intensity pattern on T2-weighted images and a low-intensity pattern on T1-weighted images. The advantage of MRI is that it has improved sensitivity and specificity when compared to ultrasound and CT in cirrhotic patients with whom it can be difficult to differentiate HCC from regenerative nodules. A systematic review found that the sensitivity was 81% (95% CI 70–91%) and specificity was 85% (95% CI 77–93%) compared with pathologic examination of an explanted or resected liver as the reference standard. The sensitivity is further increased if gadolinium contrast-enhanced and diffusion-weighted imaging are combined. MRI is more sensitive and specific than CT.Liver image reporting and data system (LI-RADS) is a classification system for the reporting of liver lesions detected on CT and MRI. Radiologists use this standardized system to report on suspicious lesions and to provide an estimated likelihood of malignancy. Categories range from LI-RADS (LR) 1 to 5, in order of concern for cancer. A biopsy is not needed to confirm the diagnosis of HCC if certain imaging criteria are met. Pathology
Macroscopically, liver cancer appears as a nodular or infiltrative tumor. The nodular type may be solitary (large mass) or multiple (when developed as a complication of cirrhosis). Tumor nodules are round to oval, gray or green (if the tumor produces bile), well circumscribed but not encapsulated.
In populations largely protected by hepatitis B vaccination, such as the United States, HCC is most often linked to causes of cirrhosis such as chronic hepatitis C, obesity, and excessive alcohol use.Certain benign liver tumors, such as hepatocellular adenoma, may sometimes be associated with coexisting malignant HCC. Evidence is limited for the true incidence of malignancy associated with benign adenomas; however, the size of hepatic adenoma is considered to correspond to risk of malignancy and so larger tumors may be surgically removed. Certain subtypes of adenoma, particularly those with β-catenin activation mutation, are particularly associated with increased risk of HCC.Chronic liver disease is rare in children and adolescents; however, congenital liver disorders are associated with an increased the chance of developing HCC. Specifically, children with biliary atresia, infantile cholestasis, glycogen-storage diseases, and other cirrhotic diseases of the liver are predisposed to developing HCC in childhood.Young adults afflicted by the rare fibrolamellar variant of hepatocellular carcinoma may have none of the typical risk factors, such as cirrhosis and hepatitis. Diabetes mellitus
The risk of hepatocellular carcinoma in type 2 diabetics is greater (from 2.5 to 7.1 times the nondiabetic risk) depending on the duration of diabetes and treatment protocol. A suspected contributor to this increased risk is circulating insulin concentration such that diabetics with poor insulin control or on treatments that elevate their insulin output (both states that contribute to a higher circulating insulin concentration) show far greater risk of hepatocellular carcinoma than diabetics on treatments that reduce circulating insulin concentration.