Shell Lesions Associated With Infection in Freshwater Aquatic Turtles.

A newly described onygenalean fungus, , has been isolated from ulcerative shell and skin lesions of freshwater aquatic chelonians. To investigate the shell lesions associated with infection and determine if any lesional features were unique to . , tissues from turtles housed in zoological institutions ( = 45) in the United States and free-living turtles ( = 5) submitted for diagnostic biopsy or necropsy were examined. Free-living turtles were from geographically distinct habitats in Florida ( = 1) and Washington ( = 4) at the time of sampling. Histologic shell sections were evaluated for the presence or absence of specific lesional features. Infection with was evaluated in all cases by screening GMS (Grocott-Gomori's methenamine silver)-stained histologic sections for the presence of morphologically consistent fungi and by quantitative PCR (polymerase chain reaction) on representative frozen tissue or formalin-fixed paraffin-embedded sections. Additionally, culture was performed for 15 cases with available fresh/frozen tissue. In total, there were 17 PCR-confirmed cases, 29 cases with morphologically consistent fungi on GMS-stained sections, and 21 cases of shell lesions without histologic or molecular evidence of infection. Epithelial inclusion cysts, defined as cystic structures within the dermis lined by keratinized stratified squamous epithelium and containing necrotic bone and keratin debris, were significantly ( < .01) associated with infection. Other significantly associated shell lesions included squamous metaplasia, hyperkeratosis, inflammation, and osteonecrosis ( < .05). This study identified characteristic shell lesions associated with infection. Further studies to prove causality are needed.