Objective To investigate two rare benign lesions, hepatocellular adenoma (H
CA) and focal nodular hyperplasia and evaluate differential diagnosis.
Methods Twenty-four consecutive patients with presumed HCA and FNH were stu
died at the Liver Cancer Institute from January 1996 to May 1999. Preoperat
ive assessment included clinical evaluation, symptoms and laboratory tests.
New imaging techniques were prospectively appraised in addition to usual t
echniques. All had hepatic resections and follow-up. Histologic examination
of surgical specimens was obtained in all cases.
Results In every instance, MH was an incidental finding. MH consists of nod
ular aggregates of cytologically normal hepatocytes with foci of intranodul
ar bile duct proliferation. In this series, patients with HCA had larger tu
mors and more often were symptomatic but the occurrence was unrelated to or
al contraceptive steroids (OCS) usage. Intralesional hemorrhage or necrosis
is common, and was seen in 75% of cases. The best imaging procedure in the
diagnosis of FNH was MRI. Color Doppler US was a useful adjunct, but CT la
cked specificity, making histological diagnosis mandatory. All patients und
erwent tumor resected were tumor-free during the follow-up.
Conclusions FNH is a distinct histopathologic entity, and is distinguishabl
e from HCA. FNH is a hyperplastic response by the liver parenchyma to a pre
-existing arterial malformation. HCA is a liver neoplasia and has the poten
tial of malignant transformation to HCC. Based on these findings, we believ
e that if the clinical suspicion of HCA or FNH is strong, resection is usua
lly the best approach if technically feasible and histologic diagnosis is m