Truffle's revenge: a pig-eating fungus.

A 77-year-old female initially presented with symptomatic mitral valve stenosis involving a bioprosthesis that had been implanted 8 months earlier for myxomatous mitral valve disease and severe valvular regurgitation. The patient was taken for a second mitral valve replacement due to stenosis. Intraoperatively, the bioprosthetic mitral valve was noted to have an unusual clot-like mass on the atrial side. Initial fungal smears were positive for yeast stains, and pathology revealed extensive colonization by thick filamentous fungus with apparent true hyphae, pseudohyphae, and yeast forms. The fungus was identified as Hormographiella aspergillata, the asexual form of Coprinus cinereus, a common inky cap mushroom that grows in the lawn. She was treated with 6 weeks of liposomal amphotericin B and then switched to voriconazole for long-term (lifelong) suppressive therapy in the setting of a new mechanical mitral valve. The only other reported case of infective endocarditis caused by a Coprinus species occurred in a 53-year-old man who had developed native aortic valve fungal endocarditis and died [J Med Microbiol (1971);4(3):370-4]. The valve isolate was identified as probable C. cinereus.