Hepatic imaging studies on patients with visceral larva migrans due to probable Ascaris suum infection

Visceral larva migrans (VLM) is a disease usually observed in children in which the larvae of animal parasites invade and reside in human tissues for long periods. Although the common causal species of VLM are Toxocara canis and T. cati, we identified three adult patients with VLM, probably due to Ascaris suum, whose diagnosis was made by specific immunoserological tests. The patients complained of respiratory symptoms, and laboratory tests showed pronounced eosinophilia, but neither larvae nor eggs were detected in stool samples. We present the findings of various imaging studies of the patients. Multiple small hypoechoic mass lesions were demonstrated by ultrasound tomography, which disappeared after anti-helminthic therapy. Hepatic mass lesions were detected as low-density areas on computed tomography, as high signal intensities on T2-weighted magnetic resonance images, as space-occupying regions in liver scintigraphy, and as yellow-white nodules in laparoscopy. Although biopsied liver tissue specimens showed marked infiltrations of eosinophiles in the portal tracts and hepatic sinusoids, neither larvae nor eggs could be identified.