A case of liver schistosomiasis japonica in which abdominal ultrasound examination was the only useful diagnostic tool

The case involves a 57-year-old Filipino woman living in Japan. Since 2020, she has been referred to a clinic for abnormal liver function and visited our hospital in May 2024 for further investigation. She had no specific symptoms, and a blood test at her first visit indicated mild liver dysfunction (AST 53 U/L, ALT 53 U/L, γGTP 106 U/L, ALP 138 U/L) and mild renal dysfunction (Cre 0.87 mg/dl, eGFR 52). She was negative for HBs antigen and HCV antibody. An abdominal ultrasound was performed, revealing marked atrophy of the right lobe of the liver, with a net-like structure due to linear high echogenicity across the entire right lobe (so-called 'network pattern') (Fig. 1a, Fig. 1b). There were no significant findings in the left lobe of the liver, and splenomegaly was not observed. Suspecting liver schistosomiasis japonica, a stool examination for eggs was conducted but yielded no detectable results. Dynamic CT, EOB-MRI, and contrast-enhanced ultrasound were performed, but no mass lesions were found in any of the tests. CT and MRI showed atrophy and deformation of the right lobe, but no findings suggestive of liver schistosomiasis japonica, such as the net-like linear high echogenicity observed on ultrasound, were seen(Fig. 1e,Fig. 1f). For definitive diagnosis, a liver biopsy was performed, and the pathological tissue showed eggs of schistosoma japonicum (Fig. 1c) and expansion of the fibrous portal area (Fig. 1d), leading to a diagnosis of liver schistosomiasis japonica.