Multifocal nodular fatty infiltration of the liver mimicking metastatic liver tumors - Diagnosis using the liver-specific late phase of Levovist-enhanced sonography

Focal nodular fatty infiltration of the liver is a pseudotumor visualized as a highly echoic lesion on sonography. On computed tomography (CT), focal nodular fatty infiltration is generally characterized by a low-density area with no mass effect.(1) Although focal nodular fatty infiltration must be differentiated from primary liver cancer, a metastatic liver tumor, or hepatic hemangioma, this can be difficult with CT or sonography alone. When differential diagnosis is difficult from imaging investigations alone, biopsy proof of the tumor is necessary before therapy is commenced. The appearance of numerous small multifocal nodular fatty infiltrations in both hepatic lobes may mimic that of metastatic liver disease, leading to incorrect therapy. Particularly if the patient has had malignant disease in the past, multifocal nodular fatty infiltrations may be misdiagnosed, and incorrect therapy may be performed without adequate examination or differential diagnosis of the primary lesion. Although magnetic resonance imaging (MRI) and fine-needle biopsy are reportedly useful in diagnosing focal fatty infiltration of the liver,(2-4) the value of enhanced sonography has not been reported in this situation. We encountered a case of multifocal nodular fatty infiltration in which findings of the late parenchymal phase of enhanced sonography with Levovist (SH U 508A; Schering AG, Berlin, Germany) were useful in ruling out malignancy.