Entomophthoromycotina

Background

Microbiology

• Cutaneous fungal infection caused by members of the order Entomophthorales
  • Basidiobolus ranarum, which leads to subcutaneous zygomycosis
  • Conidiobolus coronatus, which causes chronic rhinofacial zygomycosis

Epidemiology

• Basidiobolus
  • Lives in the intestines of many amphibians i.e. frogs, toads, salamanders, often in their feces as well as decaying fruits and soil
  • Tropical and subtropical but expanding into US
• Conidiobolus more common in India, Asia, and Saudi Arabia

Clinical Manifestations

Basidiobolus

• A single enlarging, painless and firm swelling in soft tissues on extremities e.g. buttocks, thighs, perineum, trunk
• As the infection progresses, they will start to develop burning sensation over the area
• There may be evidence of a diffuse bluish discoloration over the swollen area

Conidiobolus

• Chronic rhinofacial zygomycosis: painless swelling of the rhinofacial region that causes substantial disfigurement. The infection itself starts at the nose and invades into the subcutaneous tissue and develops into large masses. The masses eventually get so big that they block the nasal passages causing discharge, chronic sinusitis or complete nasal passage obstruction. Described as “facial elephantiasis”.
• It does not disseminate as it is not angioinvasive.
• Mainly infects adults males, disease often occurs after having inhaled the spores into the nasal cavities or through trauma

Diagnosis

• Needs tissue and culture for diagnosis

Culture

• On KOH-Calcofluor, shows broad, thin-walled and pauci-septate or aseptate fungus
• Rapid-growing in culture
• Microscopically looks similar to Mucoromycotina, with wide, pauci-septate hyaline mold form
• Conidiobolus can have “beaked” shape on spores, with a spore that has secondary spores attached to it
• Basidiobolus also has spores with a beak.

Biopsy

• Strong eosinophilic reaction in tissue histopathology.

Management

• Treated with surgical excision and antifungals
• Combination of saturated solution of potassium iodide and itraconazole