Mycotic lymphadenitis in cattle and Swine

Lymph nodes with granulomatous mycotic lesions from 100 cattle and 9 pigs were examined. More than 90% of cases of mycotic lymphadenitis in cattle occurred in the mesenteric nodes, whereas in swine lesions occurred at multiple sites. All observed mycotic infections were caused by zygomycetes. Histologically the granulomas were characterized by necrosis, mineralization, and fibrosis with infiltration of eosinophils, neutrophils, lymphocytes, and giant cells. Mucoraceous-type hyphae were identified in most of the lesions, and Absidia corymbifera, Rhizopus rhizopodiformis, and R. oryzae were isolated. Within the lesions, chlamydospores were produced by R. rhizopodiformis. Mycelia in a few lesions were suggestive of infections with fungi of the Mortierellaceae and Entomophthoraceae.