Ch. 18 - Fungal infections Flashcards
Tinea
Non-pigmented hyphae in stratum corneum, which may be parakeratotic or have inflammatory cells.
Bullous tinea
Nonpigmented hyphae in stratum corneum, with massive papillary dermal edema (resembles polymorphous light eruption or Sweet’s syndrome).
Onychomycosis
PAS-positive hyphae in subungual debris
Tinea versicolor
Loose hyperkeratosis with groups of round spores and short hyphae in stratum corneum (“ziti and meatballs”).
Candidiasis
Pseudohyphae in stratum corneum (often vertically oriented) with neutrophils and hyperkeratosis.
Coccidioidomycosis
Large uniform spherules with lacy/granular cytoplasm. Refractile wall.
Cryptococcosis
Pleomorphic encapsulated yeast. Amount of capsular material inversely proportional to granulomatous infiltrate.
Blastomycosis
Pseudoepitheliomatous hyperplasia with intraepidermal pustules. Few organisms within giant cells. Broad-based budding.
Paracoccidioides
Small yeast without thick refractile wall. Mariner’s wheel pattern of budding.
Histoplasmosis
Small uniform dots within histiocytes, each surrounded by a pseudocapsule. Narrow-based budding.
African histoplasmosis
(organism?)
Larger uniform dots with pseudocapsule. Looks like lobomycosis.
Histoplasma duboisii
Lobomycosis (keloidal blastomycosis)
(organism?)
Large organisms with pop-bead chain appearance within histiocytes.
Lacazia loboi
Sporotrichosis
Stellate abscess with granuloma containing rare cigar-shaped yeasts
Eumycetoma
Sinus tracts filled with neutrophils. Central grains made up of fungal hyphae with club-shaped accumulations of immunoglobulins (Splendore-Hoeppli phenomenon)
Acinetomycetoma
Sinus tracts filled with neutrophils. Central grains made up of filamentous bacteria with smooth Splendore-Hoeppli phenomenon at periphery.
Tinea nigra
(organism?)
Gold to brown hyphae in stratum corneum of acral skin.
Hortaea werneckii
Phaeohyphomycosis
(organism?)
Pigmented thick-walled hyphae in tissue with vesicular swelling.
Many black molds (dematiaceous fungi, mildew)
Chromomycosis (chromoblastomycosis)
Pseudoepitheliomatous hyperplasia with intraepidermal pustules. Round copper-colored Medlar bodies.
Mucormycosis
Broad, hollow, 90-degree branching refractile hyphae with vesel invasion and tissue necrosis.
Entomophthoromycosis
Indolent infection that resembles zygomycetes.
Hyalohyphomycosis
(organism?)
Narrow, non-pigmented hyphae in tissue invading vessels causing tissue necrosis.
(any invasive mold excluding zygomycetes)
Protothecosis
(organism?)
Morulae or eyeball collections of Prototheca.
Rhinosporidiosis
(organism?)
Huge sporangia with many endospores. Can resemble coccidoides.
Rhinosporidium (but Microcystis aeruginosa is synergistic)
Tinea
