RESUMO
A boy with known autism spectrum disorder was transferred to our department due to a rapidly worsening respiratory situation. The patient's history revealed previous treatment with albendazole against a Toxocara infection 2 weeks prior in Poland. Blood analysis showed such severe eosinophilia and markedly elevated levels of IgE that, initially, a hematologic malignancy was suspected. However, diagnostic workup including autoimmune diagnostic, molecular genetic testing, fluorescence in situ hybridization (FISH), bone marrow aspiration, and parasitological testing led to the diagnosis of an insufficiently treated Toxocara infection. Treatment with albendazole and prednisone (six cycles for 4 weeks each) was administered. This treatment regime led to prompt improvement of symptoms and normalization of laboratory findings.