Basidiobolomycosis and conidiobolomycosis are the 2 clinical entities classified as entomophthoramycosis:
- Basidiobolus ranarum is responsible for basidiobolomycosis in human infection.
- Conidiobolomycosis is an infection caused by Conidiobolus coronatus or Conidiobolus incongruus.
This summary will focus on subcutaneous entomophthoramycosis. The other 2, rhinofacial and visceral/disseminated, are discussed separately: see Rhinofacial conidiobolomycosis and Disseminated basidiobolomycosis, respectively.
Subcutaneous entomophthoramycosis, also known as cutaneous basidiobolomycosis, is almost exclusively characterized by infection with B. ranarum, a fungus that can be found in soil and decaying vegetation. It shares the same geographic distribution as rhinofacial entomophthoramycosis, occurring mostly in tropical Africa, South and Central America, Jamaica, Southeast Asia, Australia, China, and India. Subcutaneous infection usually occurs by traumatic inoculation.
In contrast to conidiobolomycosis, basidiobolomycosis is seen mostly in children (younger than 20 years) and has a less pronounced male dominance (male-to-female ratio 3:1).
The skin lesions often involve the trunk, arms, shoulder, axilla, thighs, perineum, and scrotum. They are acquired by minor skin trauma or insect bites. The use of Basidiobolus fungi-contaminated tree leaves to clean after a bowel movement is thought to be the mode of transmission of perineal infection. The cutaneous lesions often begin as nodules and swellings associated with inflammatory cellulitis that become "woody" and hard, with abrupt edges and surrounding satellite nodules. The involved skin sometimes becomes hyperpigmented but without overlying skin ulceration.
Related topic: Mucormycosis
B36.8 – Other specified superficial mycoses
240786004 – Cutaneous basidiobolomycosis
Pythiosis – Cutaneous fungal infection caused by Pythium insidiosum; clinical features can resemble subcutaneous entomophthoramycosis. It can be differentiated by the appearance of motile Pythium hyphae on culture.
Of note, entomophthoramycosis usually occurs in immunocompetent individuals as opposed to other invasive mold infections, which more often affect immunocompromised hosts.
The differential diagnosis of a nodule is broad. For the differential diagnosis of subcutaneous entomophthoramycosis, also consider:
- Mucosal leishmaniasis
- Cat-scratch disease
- New World cutaneous leishmaniasis
- Penicillium marneffei
- African trypanosomiasis
- American trypanosomiasis
- Cutaneous tuberculosis
- Buruli ulcer
- African histoplasmosis