Clinicopathological Features of Focal Nodular Hyperplasia-Like Nodules in 130 Cirrhotic Explant Livers

Abstract

Focal nodular hyperplasia-like nodules (FNH-like nodules) are focal lesions occurring in liver cirrhosis and are morphologically very similar to classical FNH in an otherwise normal liver. They are sometimes misdiagnosed as hepatocellular carcinoma (HCC) on imaging because both types of lesions show arterial-phase enhancement. Although the morphological, immunohistochemical, and imaging features of FNH-like nodules are well-known, their pathogenesis and role in hepatocarcinogenesis have not been studied in detail. Therefore, we performed a detailed pathological evaluation of 130 cirrhotic explant livers and correlated these data with the clinical features of the patients. All cirrhotic explant livers were uniformly sliced at 5-mm intervals and all detected focal lesions were microscopically classified according to internationally accepted criteria. The obtained data regarding FNH-like nodules were then correlated with other pathological findings and with clinical data obtained during pretransplant evaluation and recorded in a database. FNH-like nodules were present in 15% of patients and their small size (75% of cases < 1 cm) appears to preclude detection by imaging in almost all cases. The presence of esophageal varices and pretransplant treatment with chemoembolization were independently and significantly associated with the presence of FNH-like nodules. There were no associations between FNH-like nodules on the one hand and low-grade dysplastic nodules, high-grade dysplastic nodules, and HCCs on the other hand. The clinicopathological features of FNH-like nodules support the hypothesis that vascular alterations in liver cirrhosis play an important role in their pathogenesis and that FNH-like nodules do not have an increased risk of malignant transformation.