Histologic examination revealed necrotizing granulomatous inflammation with abundant yeast and broad-based, branching hyphal-phase organisms consistent with Zygomycetes. Gomori methenamine silver staining confirmed the presence of fungal organisms. Tissue culture on blood agar revealed wooly dense colonies that covered the agar plate within 48 hours. Staining with lactophenol cotton blue revealed broad, nonseptate hyphae (6-15 μm) and rhizoids (rootlike hyphae) at the branching points of sporangiophores, characteristic of Rhizopus.
Crusted Violaceous Plaques on an Immunocompromised Host—Diagnosis. Arch Dermatol. 2007;143(3):417-422. doi:10.1001/archderm.143.3.417-g