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Cutaneous basidiobolomycosis
Other Resources UpToDate PubMed

Cutaneous basidiobolomycosis

Contributors: Zaw Min MD, FACP, Ricardo M. La Hoz MD
Other Resources UpToDate PubMed


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.

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.
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 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

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Differential Diagnosis & Pitfalls

Other invasive fungal infections should be considered as differential diagnoses, including:

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:
  • Mucocutaneous leishmaniasis
  • Actinomycosis
  • South American bartonellosis
  • Cat-scratch disease
  • Coccidioidomycosis
  • Cutaneous leishmaniasis
  • Cutaneous nocardiosis
  • Talaromyces marneffei infection
  • Sporotrichosis
  • African trypanosomiasis
  • American trypanosomiasis
  • Cutaneous tuberculosis
  • Buruli ulcer
  • Gnathostomiasis
  • African histoplasmosis
  • Leprosy
  • Lobomycosis
  • Melioidosis
  • Paracoccidioidomycosis
  • Rhinoscleroma
  • Yaws

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Last Updated:07/18/2023
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Cutaneous basidiobolomycosis
A medical illustration showing key findings of Cutaneous basidiobolomycosis : Buttocks, Edema, Face, Smooth nodule, Trunk, Insect bite
Copyright © 2024 VisualDx®. All rights reserved.