Morphology, description, diagnosis, and comment for fungal infections that present with hyphae or pseudohyphae in tissues. Morphology, description, diagnosis, and comment for fungal infections that present with hyphae or pseudohyphae in tissues. All photographs are of Grocott methenamine silver (GMS)-stained specimens except for the inset in the fourth row, which is a Fontana-Masson stain. The brown color observed in the fungal element is melanin. For each type of infection, alternative testing and correlation with culture, epidemiologic, and clinical features are necessary. (The photograph in the fourth row is reprinted from the CDC Public Health Image Library collection.) Jeannette Guarner, and Mary E. Brandt Clin. Microbiol. Rev. 2011; doi:10.1128/CMR.00053-10