Echinococcosis (hydatid disease) in Missouri: diagnosis by fine-needle aspiration of a lung cyst.

Echinococcus granulosus was diagnosed by fine-needle aspiration cytology of a lung cyst in a 6-yr-old white female in central Missouri. No adverse reaction occurred following the aspiration. The cytologic sample yielded clear fluid containing numerous clearly identifiable protoscoleces diagnostic for echinococcosis using routine PAP staining. Since hydatid disease is extremely uncommon in the Midwest, it had not initially been considered in the differential diagnosis. The infection was probably not indigenous to Missouri, since the patient lived the first 3 1/2 yr of life in Alaska, where the organism is endemic. This can only be speculative, however, since echinococcal organisms are found in wildlife in the Midwest.