Intrahyphal hyphae in corneal tissue from a case of keratitis due to Lasiodiplodia theobromae.

Lasiodiplodia theobromae, a recognized plant pathogen, was isolated in culture from a case of human mycotic keratitis. Chemotherapy with a variety of azoles was unsuccessful and the lesion was removed surgically. Electron microscopy of thin sections of the excised corneal tissue revealed several examples of intrahyphal hyphae, a unique process described previously in in vitro cultures of various zoopathogenic fungi. We believe this to be the first report of the presence of intrahyphal hyphae in parasitized animal or human tissue. The demonstration of this process in vivo is thought to be consistent with the hypothesis that intrahyphal hyphae might represent an attempt by the invading fungus to survive in an otherwise unfavourable environment.