Conidiobolomycosis in sheep: reevaluation of three cases previously diagnosed as enzootic ethmoid tumor

Conidiobolomycosis is an infection caused by fungi of the genus Conidiobolus spp. that is associated with a granulomatous rhinitis in humans and animals. In sheep, the disease is clinically characterized by respiratory changes, exophthalmia, craniofacial asymmetry, and fever. Microscopically, there are multifocal granulomas containing intralesional hyphae. For a long time, this disease was diagnosed as Enzootic Ethmoid Tumor. This report described three cases of conidiobolomycosis that had been previously diagnosed as Enzootic Ethmoid Tumor. Samples of nasal cavity, lung, parotid gland, and lymph node from three sheep submitted to histopathological examination in 1979 were retrieved in 2010 for a new histological, histochemical, and immunohistochemical evaluations. Paraffin-embedded tissue sections were stained with Hematoxylin-Eosin, Grocott's Metanamine Silver, and Periodic Acid Schiff. Immunohistochemistry was performed on paraffin embedded tissues using anti-cytokeratin primary antibody. Based on histopathology, histochemistry, and immunohistochemistry, the diagnosis of conidiobolomycosis was confirmed in three sheep, which had been previously diagnosed as Enzootic Ethmoid Tumor in 1979.