Mycology - Subcutaneous Mycoses

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Chromoblastomycosis

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• Chronic fungal infection acquired via traumatic inoculation
• Primarily involves skin and subcutaneous tissue (of mainly feet and legs)
• Develop papule at site of infection that slowly spreads to form warty or tumor-like lesions (cauliflower-like)
• Brown sclerotic bodies, non-budding structures occurring singly or in clusters, seen in tissues is diagnostic for chromoblastomycosis
• Secondary infection and ulceration may occur

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Acrotheca (rhinocladiella) type sporulation

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test tube brush

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Cladosporium type sporulation

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Elliptical conidia in chains

Each conidium connected to the adjacent one via a scar-like attachment known as a “disjunctor” Branched conidium-bearing cells appear like a shield due to having 3 scars (may or may not have)

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Phialophora type sporulation

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Flowers in a vase

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Fonsecaea pedrosoi and Fonsecaea compacta

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• Cause chromoblastomycosis
• Dematiaceous (brown) septate hyphae Conidiophores cylindrical, slightly inflated at the tip
• Produce all three types of sporulation

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Phialophora verrucosa

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• Cause chromoblastomycosis
• Hyaline to dematiaceous septate hyphae
• Phialophora type sporulation only

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Cladophialophora carrionii

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• Causes chromoblatomycosis
• Dematiaceous septate hyphae
• Cladosporium type sporulation only (tends not to have shield cells)

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Mycetoma

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• Chronic granulomatous infection
• Triad of symptoms: Swelling of subcutaneous tissue causing tumor-like deformities
• Multiple sinus tracts that tunnel through subcutaneous tissue to surface
• Drainage contains granules which may be white, yellow, red, or black

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Pseudallescheria boydii (telemorph)/Scedosporium apiospermum (anamorph)

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causes mycetoma

sexual and asexual forms

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Scedosporium apiospermum - microscopic examination

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anamorph phase

• Septate hyphae
• One-celled, egg-shaped conidia (anneloconidia) at the tips of conidiaproducing hyphae (annellophores)

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Pseudallescheria boydii

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Dark-pigmented cleistothecia (multicellular structures in which asci and ascospores are formed and held) are found below the surface of the agar

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Acremonium

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• causes mycetoma
• Hyaline septate hyphae
• Unbranched tapering conidiophores support closely packed balls of sickle or elliptical shaped conidia

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Phaeohyphomycosis

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• Fungal infections that are caused by dematiaceous fungi
• No sclerotic bodies or granules in tissue. Instead yeast-like cells or hyphae are seen in tissue
• traumatic implantation or inhalation

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Alternaria

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• causes phaeohyphomycosis
• Conidiophores which may zigzag.
• Conidia are large and may resemble the spindle macroconidia of the dermatophytes. T
• he conidia have horizontal and vertical septations which make them look like layers of bricks

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Bipolaris

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• causes phaeohyphomycosis
• Conidiophores bend at the formation of each conidium, giving a knobby appearance. The conidia are oval, thick-walled, and contain four or five septations.

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Curvularia

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• causes phaeohyphomycosis
• Knobby conidiophores with boomerang shaped conidia that contain four cells

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Exophiala jeanselmei

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• causes phaeohyphomycosis
• Slender conidiophores (annelides). Conidia are extruded into the environment. The annelide tends to taper to a point with a cluster of oval conidia

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Wangiella dermatitidis

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• causes phaeohyphomycosis
• Tube-like phialides without collarettes elicit terminal balls of conidia. The conidia tend to fall down to the sides of the phialides.
• Morphologically resembles Exophiala jeanselmei. However Wangiella dermatitidis will grow at 42C; Exophiala jeanselmei will not

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Sporotrichosis

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• Known as the “rose gardener’s” disease
• Primary lesion starts as a small, non-healing ulcer (on hand or finger)
• With time, nodular lesions of skin or subcutaneous tissue at point of contact develop
• Later, can involve lymphatic channels and lymph nodes draining the region

• caused by dimorphic Sporothrix schenckii

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Sporothrix schenckii - mold phase

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• Hyaline, septate hyphae
• Flowerette arrangement: conidia hyaline to brown, ovoid, thin-walled, grouped in rosettes at the tip of the conidiophore.
• Conidia are attached to conidiophore by an individual, delicate, threadlike structure (denticle)
• Can be confused with Acremonium (which has no yeast phase)

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Sporothrix schenckii - yeast phase

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Yeast ovoid, elongate or cigar-shaped, producing one or several buds