Esophageal and proventricular cryptosporidiosis in a chicken.

Examination of hematoxylin-and-eosin-stained sections of chicken esophagus and proventriculus revealed Cryptosporidium-colonized surface squamous and mucous gland columnar epithelial cells. This chicken also had malignant lymphoma (lymphosarcoma). The hypothesis that infection by Cryptosporidium sp. was either preceded by or followed by herpesvirus infection, immunosuppression, and neoplasia cannot be refuted. Clinicians and pathologists should be aware that esophageal and proventricular cryptosporidiosis can occur in chickens; they should also be aware that mild inflammation and necrosis can accompany parasitism.