Entomophthoramycosis (also known as entomophthoromycosis) is the disease caused by fungi belonging to the order of Entomophthorales. Due to a change in high-level fungal taxonomy, the class Zygomycetes was renamed Glomeromycetes. Glomeromycetes include 2 orders of fungi, namely Mucorales and Entomophthorales.
Conidiobolomycosis and basidiobolomycosis are the 2 clinical entities classified as entomophthoramycosis:
Conidiobolomycosis is an infection caused by Conidiobolus coronatus or Conidiobolus incongruus.
Basidiobolus ranarum is responsible for basidiobolomycosis in human infection.
Both clinical entities are regarded as a rare chronic non-angioinvasive mycotic disease affecting otherwise healthy individuals in tropical areas of Africa, South America, and Asia. There are 3 recognized clinical forms: rhinofacial, subcutaneous, and visceral/disseminated. This summary will focus on rhinofacial entomophthoramycosis. The other 2, subcutaneous and visceral/disseminated, are discussed separately: see Cutaneous basidiobolomycosis and Disseminated basidiobolomycosis, respectively.
Rhinofacial entomophthoramycosis (rhinofacial conidiobolomycosis, rhinoentomophthoramycosis) is a disease caused by C. coronatus and more rarely by C. incongruus or B. ranarum. It occurs mostly in tropical Africa, South and Central America, Jamaica, Southeast Asia, Australia, China, and India. There have been sporadic cases reported in the United States.
Rhinofacial entomophthoramycosis is predominantly a disease of adults, with a high male preponderance (male-to-female ratio 8:1). Conidiobolus fungi are ubiquitously found in soil, decaying vegetation, and known pathogens of insects and spiders. These fungi are also inhabitants of the gastrointestinal tract of reptiles and amphibians. Infection is thought to be acquired through inhalation of fungal spores that deposit on the nasal mucosa, or from minor mucosal trauma from frequent picking of the nose.
Typical clinical manifestations include nasal discharge, epistaxis, and nasal obstruction, which usually start unilaterally followed by progression to bilateral paranasal sinuses, cheeks, and upper lip swelling, resulting in "hippopotamus-like" or "lion-like" facial disfiguration in untreated cases. It usually takes several months to years to progress to the facial distortion stage. The lesions are characteristically limited to the face and nose without bony involvement, skin ulceration, or intracranial extension. There have been reported incidents of dysphagia and laryngeal obstruction from nasofacial conidiobolomycosis.
Other invasive fungal infections should be considered as differential diagnoses, including:
Rhinocerebral mucormycosis – Rule out in patients with suspected rhinofacial conidiobolomycosis because of the similarities of fungal hyphae, but Mucorales infection typically presents acutely, with rapidly progressive opportunistic mycoses causing frank angioinvasion with significant tissue necrosis.
Of note, entomophthoramycosis usually occurs in immunocompetent individuals as opposed to other invasive mold infections, which more often affect immunocompromised hosts.