[Lymphoma-simulating presentation of focal nodular hyperplasia (FNH) of the liver]

A 51-year-old woman, who had taken oral contraceptive drugs for 11 years, was referred to our Unit for examination of an asymptomatic 3.6 x 4.1 cm hypoechoic liver mass found by ultrasound examination carried out in the course of gynecological screening.

Laboratory evaluation revealed mild elevated liver enzymes. Computed tomography exhibited a hypervascularized lesion in segment 4 of the liver resembling a hemangioma or focal nodular hyperplasia but FNH was favored since magnetic resonance imaging showed a central scar within the hepatic lesion. Hepatobiliary scintigraphy was not typical thus an ultrasound-guided needle biopsy was performed. Histological examination revealed lymphoma-like infiltrates close to normal liver cells. However, the molecular biological examination showed oligoclonality of the infiltrating T-cells. Blood examinations, bone-marrow punctuation and CT thorax scan did not show any other lymphoma-like lesion.

After 5, 10 and 15 months the untreated patient was re-examined by MRI. The focal lesion showed an unchanged size and again a FNH-typical imaging. Liver-specific contrast enhancement was not suggestive for lymphoma. The lymphocytes were interpreted as an atypical lymphoid inflammatory infiltrate of a non-neoplastic lesion of the liver.

The focal nodular hyperplasia can be a very difficult diagnosis in imaging and histopathological examinations. The lymphoma of the liver can be a rare but possible differential diagnosis.