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

Abstract

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.

Visceral larva migrans syndrome: analysis of serum cytokine levels in children with hepatic lesions confirmed in radiological findings

“…Eosinophilia is one of the most characteristic findings in Toxocara sp. infections in both humans and animals (15,19,20). The eosinophil counts peak on the fourth day of infection and remain elevated for at least 30 days.…”

Nematode infection of the liver mimicking metastasis of malignant melanoma

“…However, because of an advanced state of necrosis of the specimen, the discrimination of the body type and thus a determination of genus and species by morphologic criteria was impossible and remains unclear. Computed tomographic hepatic imaging of lesions caused by Ascaris species usually show low-density areas with poorly defined margins and early phase arterial enhancement (10). Because the larvae of A. suum are unable to mature in human beings or to pass eggs into the human intestine, eggs are not found in stools (11).…”

Hepatic Toxocariasis with Atypical CT and MR Imaging Findings: a Case Report

“…The slow migration of T. canis larvae often results in a periportal eosinophilic infiltrate, abscess, or granuloma. The lesions usually appear as multiple small, ill-defined, oval or elongated, low attenuation nodules on dynamic CT in the portal venous phase (3,7,8). Eosinophilic abscesses may, in some cases, appear as persistent low-attenuation lesions in the arterial, portal venous, and equilibrium phases (2).…”