Focal Nodular Hyperplasia of the Liver

Radiologic-Pathologic Correlation

Abstract Introduction Clinical Features

Pathologic Features Radiologic Features Differential Diagnosis Treatment And Prognosis

Summary Source Information References

Introduction

Focal nodular hyperplasia (FNH) is the second most common benign hepatic tumor (after hemangioma), constituting about 8% of primary hepatic tumors in an autopsy series (1). FNH is focal not diffuse: It is a localized, well-delineated mass within an otherwise normal liver. FNH is nodular: It is composed of multiple, spherical aggregates of hepatocytes held together in a fibrous meshwork with a dominant scar or scars. FNH is a hyperplasia: It is a proliferation of normal, nonneoplastic hepatocytes that are abnormally arranged.

FNH probably represents a local hyperplastic response of hepatocytes to a congenital vascular anomaly (2,3). In support of this theory, FNH has been found in association with cavernous hemangiomas, and many cases of FNH have been associated with vascular malformations of various other organs and neoplasms of the brain (4,5,6). Intermediate lesions, that is, lesions with characteristics of both cavernous hemangiomas and FNH, have been reported (5). A rare transitional lesion, reported as a mixed hamartoma, which is found most often in infants and children, has similarities to both FNH and hemangioma (1,7). Vascular lesions and FNH thus share an intimate developmental heritage.

It is hypothesized that a congenital vascular malformation (either an arteriovenous shunt or localized hyperperfusion) triggers focal hepatocellular hyperplasia. At pathologic examination, anomalous arterial branches, unaccompanied by portal venous branches, have been seen feeding the numerous small lobules that constitute the FNH lesion (2). Just as hyperplasia and hypertrophy are seen around vascular malformations in the extremities, similar hepatic hyperplasia is seen in the liver.

This report is based on a review of the literature and over 50 cases of FNH with cross-sectional imaging studies accessioned to the AFIP (Armed Forces Institute of Pathology) radiologic pathology archives from January 1980 to January 1994. Representative examples of these cases are illustrated in this article, which examines the clinical, pathologic, and radiologic features of FNH. We also discuss the differential diagnosis, treatment, and prognosis for this lesion.

Abstract Introduction Clinical Features

Pathologic Features Radiologic Features Differential Diagnosis Treatment And Prognosis

Summary Source Information References