Zygomycosis

Zygomycosis



Basic Information image



Definition


Deep, progressive, and rapidly invasive subcutaneous mycosis caused by fungi belonging to the class Zygomycetes (includes Entomophthorales and Mucorales)



Synonym(s)


Phycomycosis, entomophthoromycosis, conodiobolosis, rhinophycomycosis, basidiobolosis, mucormycosis



Epidemiology



Geography and Seasonality




• Zygomycosis occurs mostly in tropical and subtropical areas (Americas, Australia, Asia, and Africa).


• In the United States, zygomycosis is most common in states along the Gulf of Mexico.



Associated Conditions and Disorders


Relatively rare opportunistic fungal infection in humans manifested with gastrointestinal, pulmonary, cutaneous, renal, or meningeal involvement. It generally affects only immunocompromised individuals.



Clinical Presentation



Disease Forms/Subtypes




• Entomophthoromycosis


image Conodiobolosis: Ulcerative granulomas on mucosa

image Basidiobolosis: Ulcerative cutaneous granulomas

• Mucormycosis: Ulcerated cutaneous granulomas



History, Chief Complaint




• Insidious onset of cutaneous granulomas, potentially fast-growing lesions.


• Nasal granulomas can go unnoticed, and the only clinical signs might be red-tinged nasal discharge and dyspnea.



Physical Exam Findings




• Basidiobolus infects the lateral aspects of the head, neck, trunk, and body (Figures 1 and 2).


image Lesions are usually single and large, nodular eroded to ulcerative granulomas associated with moderate to severe pruritus and oozing of serosanguineous discharge.

image Moderate to severe pruritus

image If excised, tissue has a thickened fibrotic dermis (pink) and might contain small, scattered areas of red surrounding a white to yellow central core (“leeches”) smaller than those seen with pythiosis.

• Conidiobolus affects almost exclusively the mucosa of the nares, nasal passages, and possibly the mouth and nasopharynx.


image Serosanguinous nasal discharge

image Single or multiple ulcerative pyogranulomas may lead to mechanical blockage of the airway, resulting in dyspnea.

image If on the external nares: Lesions appear similar to basidiobolus infection.

image If in nasal passages and nasopharynx: Firm nodules covered by edematous, focally ulcerated mucosa.

• Mucormycosis: Single or multiple ulcerated cutaneous granulomas of the limbs, muzzle, and lips


image

FIGURE 1 Basidiobolus infection.


image

FIGURE 2 Example of zygomycosis.



Etiology and Pathophysiology




• Zygomycetes are ubiquitous saprophytic fungi in soil and decaying vegetation and may be present as part of the normal flora of skin and haircoat of horses.


• Infection may be caused by several related fungal species belonging to two orders under the class Zygomycetes, phylum Zygomycota:


image Entomophthorales (includes genera Conidiobolus and Basidiobolus)

image Mucorales (includes genera Rhizopus, Mucor, Absidia, and Mortierella)

• Infections are thought to develop secondary to wound inoculations.


• After inoculation, the fungi develop in the dermis, resulting in a pyogranulomatous inflammation.

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Zygomycosis

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