Little is known about preexisting lesions in livers of children with
pyogenic liver abscess (PLA). Study of these lesions may elucidate possible predisposing factors for the disease. In Vitória, state of Espirito Santo, Brazil, PLA in children is frequently associated with helminthic
infections and
eosinophilia. We hypothesize that
nematode infection with larvae migrating through the liver is a predisposing factor for PLA, because the
infection induces
immunomodulation and likely trapping of bacteria in liver
granulomas. In this report, we describe observations of 22 cases of PLA in children studied at autopsy (16 cases) or in surgical biopsies (6 cases), including 17 boys and 5 girls ranging in age from 1 to 13 years (mean 4.6 years, median 3.5 years). Multiple
abscesses in both lobes were found in 13 cases and a single
abscess was found in the right lobe in 10 cases. All cases showed histologically classical pyogenic
inflammation without morphological evidence of
amoebiasis. In six cases there were
granulomas similar to those caused by
larva migrans visceralis (from Toxocara or other nematodes) in liver tissue not affected by the
abscess. Nematode
antigens in central areas of
necrosis of
granuloma in all six cases and fragments of a larva, possibly of Toxocara, were found on samples immunohistochemically stained with polyclonal anti-Toxocara
antibodies. There were numerous eosinophils in
abscesses with Charcot-Leyden crystals. Eosinophils were found frequently in portal triads far from the
abscess wall. In four cases, in which bile duct
ascariasis was found, worms were noted in the bile ducts, and eggs were found in liver parenchyma surrounding the
abscess in two cases.
Foreign-body granulomas were found in one case in which penetrating
trauma was the cause of
abscess. In one case there was one histiocytic
granuloma whose origin was not determined. The observation of six cases of
granuloma similar to
larva migrans visceralis (or produced by other nematode larva) in liver tissue not directly affected by the
abscess supports the hypothesis that helminth
infections with larva migrating through the liver are a predisposing factor for
pyogenic hepatic abscess in children.