abstract

A 6-year-old intact male California sea lion (Zalophus californianus) presented two weeks following tooth extraction with mild diffuse hind flipper swelling, numerous 0.25-1.0 cm nodules and ring-lesions on the rear flippers, and several 1-3 cm firm, round, raised, dermal nodules on the ventral abdomen, thought to be a hypersensitivity reaction but unresponsive to diphenhydramine. Over the following days the nodules increased in size and number, spreading to the foreflippers and muzzle. Skin biopsies, blood, and bacterial cultures were obtained. Cultures, complete blood count (CBC), and serum biochemistry were unremarkable. Histopathologic evaluation of biopsies revealed granulomatous dermatitis due to atypical fungal infection. Itraconazole treatment was initiated. No significant fungal cultures were grown; initial fungal PCR tests of biopsy tissues produced an amplicon having significant sequence identity with a cystofilobasidiomycete, a rare fungus belonging to a subclade including several Cryptococcus spp. Dermal nodular lesions spread dramatically, and the animal developed severe axillary lymphadenopathy despite itraconazole therapy. Five weeks after beginning itraconazole treatment the animal exhibited signs of systemic disease (inappetence, lethargy, and periods of generalized trembling). Follow-up bloodwork revealed a neutrophilic leukocytosis with monocytosis and elevated fibrinogen. Treatment with voriconazole was initiated but the animal died ten days later following a grand mal seizure. Histopathologic evaluation of necropsy tissues revealed fungal dissemination throughout dermis and lymph nodes, granulomatous foci with yeast cells in kidneys and heart, hepatocellular necrosis and skeletal muscle myositis. Additional molecular testing is pending to confirm what could be the first case of cystofilobasidiomycosis in a marine mammal.

acknowledgements

We are very grateful to Drs. Brian Wickes and Deanna Sutton of the University of Texas Health Science Center for their assistance with fungal identification, Lynn Hinckley of the University of Connecticut for assistance with culture preparations, Drs. Akinyi Nyaoke and Kathleen Deering for necropsy assistance, and to the Mystic Aquarium & Institute for Exploration California Sea Lion staff for their excellent animal care.