Colon non tumor
Infectious colitis (specific microorganisms)
Basidiobolomycosis

Author: Nalini Gupta, M.D., D.N.B., PDCC (see Authors page)

Revised: 28 February 2017, last major update February 2017

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PubMed Search: basidiobolomycosis
Cite this page: Basidiobolomycosis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colonbasidio.html. Accessed December 17th, 2017.
Definition / general
  • Basidiobolomycosis is a rare fungal infection caused by environmental saprophyte Basidiobolus ranarum
  • It is a member of the order Entomophthorales of the class zygomycetes
  • The zygomycetes include two fungal orders:
    • Mucorales, involving mainly immunocompromised patients, and
    • Entomophthorales, which causes infection in immunocompetent individuals (J Korean Surg 2012;83:325)
  • Basidiobolomycosis is endemic in tropical and subtropical regions of Africa, Latin America, Middle East and Asia (Curr Pediatr Res 2013;17:1)
  • It mainly involves skin and subcutaneous tissue and rarely infects the gastrointestinal tract
  • First case of visceral basidiobolomycosis (GIB) was reported in 1964 (Trans R Soc Trop Med Hyg 1964;58:242)
Essential features
  • Basidiobolomycosis is a rare fungal infection caused by Basidiobolus ranarum
  • Causes infection in immunocompetent individuals
  • Is endemic in tropical and subtropical regions
  • Mainly involves skin and subcutaneous tissue, visceral involvement is rare
  • Infection is caused by ingestion of contaminated food or use of contaminated toilet paper
  • Abdominal pain and fever are most common presenting features
  • Histology shows broad septate thin walled fungal hyphae with the Splendore-Hoeppli phenomenon
  • Culture is gold standard for diagnosis
  • Treatment: combined surgery and medical therapy with antifungals
  • Prognosis poor in pediatric patients
ICD-10 coding
  • ICD-10-CM: B46.8 - other zygomycoses
Epidemiology
Sites
  • Mostly cause chronic infection in the skin and subcutaneous tissue
  • May cause infection in the stomach, small intestine, colon and liver
Pathophysiology
  • Infection is acquired by ingestion of infected food (e.g., people with pica) and using contaminated papers for cleaning the skin (e.g., toilet papers)
  • Possibly due to ranitidine, which can decrease gastric acidity and allow fungal survival after gastric passing (Iran J Med Sci 2015;40:90)
  • Smoking can decrease mucosal WBC function and facilitate fungal infection by B. ranarum (Clin Infect Dis 2012;54:1685)
Etiology
  • Basidiobolus ranarum
Clinical features
Diagnosis
  • Based on characteristic histopathology findings of fungal hyphae (the Splendore-Hoeppli phenomenon) and culture of B. ranarum from the tissue specimen
  • The gold standard for definite diagnosis is culture
  • Macroscopically, colonies are yellowish gray in color with a waxy appearance and many radial folds (J Med Microbiol 2012;61:1770)
Laboratory
  • Eosinophilia and high ESR (erythrocyte sedimentation rate)
  • Elevated levels of cytokines such as IL4, IL10, TNFα (TH2 type cytokines) (J Clin Microbiol 2001;39:2360)
Radiology description
Radiology images

Images hosted on other servers:

MRI before surgical intervention and treatment

Generalized markedly thickened
wall of the small bowel
with edematous changes

Poor prognostic factors
  • Pediatric age group at presentation
  • Delayed treatment
Case reports
Treatment
  • Combined surgery and antifungal treatment for a variable period of time (6 months to 2 years) (J Pediatr Surg 2012;47:949)
  • Itraconazole, an antifungal agent is the most common drug used
Clinical images

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Subcutaneous nodule over the left knee

Gross description
  • Fungus involves the nonmucosal layers such as submucosa and subserosa of the GI tract, hence endoscopic biopsies, which are superficial and small, usually fail to detect the fungal hyphae (Saudi Med J 2013;34:1068)
Gross images

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Edematous left colon

GI basidiobolomycosis

Adherent small bowel loop

Postmortem liver

Microscopic (histologic) description
  • Marked infiltration of eosinophils
  • Mixed infiltration of PMN leukocytes and granulomatous inflammation
  • Thin wall and broad hyphae surrounded by eosinophilic material, which are easily seen by hematoxylin and eosin staining; however periodic acid-Schiff (PAS) and gomori methenamine silver (GMS) can intensify the fungal wall staining
  • Zygospores which are very similar to trophozoites of amoeba (Clin Infect Dis 2001;32:1448)
Microscopic (histologic) images

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Staining of the tissue biopsy from left retrocolic mass

Histopathology of surgically resected abdominal mass

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Fig 7, H&E: granulomatous inflam-
mation around fungal structure;
Fig 8, PAS: broad thin walled septate
fungal hyphae containing zygospores


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Broad hyphae with septation

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Splendore-Hoeppli phenomenon

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Zygospore

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Periodic acid-Schiff stain


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Fungal hyphae

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Liver biopsy

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Spore forms

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Various images

Cytology description
  • Broad septate thin walled fungal hyphae along with eosinophils
Positive stains
Differential diagnosis