Toxocarosis and putative DRESS syndrome in an oncological patient: a case report.

Toxocarosis is a parasitic infection caused by Toxocara canis or Toxocara cati. Their definite hosts are the domestic dog and cat, where their adult forms live within the lumen of the small intestine. In humans, infective larvae hatch after ingestion of eggs, but the juvenile stages fail to develop into mature adult worms. Instead, they migrate through the body with the potential to affect virtually every body site. DRESS syndrome (drug reaction with eosinophilia and systemic symptoms) is a serious cutaneous drug reaction, which also involves other organ systems. We report on a 45-year-old man who was admitted with fever up to 40 °C, skin rash and pruritus not responding to amoxicillin/clavulanic acid. Laboratory results showed a slightly elevated white blood cell count, with 62 % eosinophils. History revealed contact to roaming cats. Travel history was unremarkable. Extensive diagnostic workup was performed, and the patient was finally diagnosed with DRESS syndrome, responded to systemic corticosteroid therapy and was discharged. Serology for Toxocara came back positive a few days later. Stool was again sent for microscopy and was found positive for Giardia lamblia, which was treated with a 5-day course of metronidazole. The patient had again developed rash and eosinophilia (62 %). Total immunoglobulin (Ig)E was 1,689 U/l (normal limit: < 100 689 U/l). Follow-up serology showed a marked increase of Toxocara TES ELISA IgG (70 U, normal limit: < 20 U), confirming toxocarosis. Antiparasitic treatment with albendazole 400 mg bid for 5 days was initiated; eosinophilia resolved; and the patient had no further complaints. Although generalized exanthema due to Toxocara has not yet been described in literature, toxocarosis is known to cause a wide spectrum of cutaneous manifestations. Whether our patient had both, a drug reaction with eosinophilia and systemic symptoms and a parasitic infection, or whether a hypersensitivity reaction to Toxocara antigen was mimicking a DRESS syndrome remains unclear.