Combined diffusion-weighted MRI and contrast-enhanced ultrasonography in diagnosing small hepatic MALT lymphoma mimicking hepatocellular carcinoma.

A woman in her 70s was referred for evaluation of a small (8 mm) hepatic nodule detected on magnetic resonance imaging (MRI). The lesion demonstrated high signal intensity on diffusion-weighted imaging (DWI) with low apparent diffusion coefficient (ADC) values, which is atypical for small hepatocellular carcinoma (HCC). Contrast-enhanced ultrasonography (CEUS) revealed washout within 60 s, which is also atypically early for HCC. Histopathological examination confirmed hepatic mucosa-associated lymphoid tissue (MALT) lymphoma. The combination of high signal intensity on DWI, a low ADC value, and early washout on CEUS is particularly useful in identifying small atypical hepatic tumors, such as MALT lymphoma, that mimic HCC.