Infectious Disease Pathology
Case 2 -
Entomophthorales Infection, most likely to be Basidobolomycosis, typically caused by Basidiobolomycosis ranarum
Alton Brad Farris, Emory University, Atlanta, GA
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A 48 year old male presented with fever, weight loss, and malaise. Surgery was performed for the clinical impression of an intestinal obstruction, and exploration of the abdomen showed an 8 cm pericecal abscess and localized cecal ulceration.
Case 2 - Figure 1
Localized eosinophilic collections were identified within the tissue. Within the collections of tissue eosinophlia, fungal forms could be identified. (H & E, Original magnification: 10x)
Case 2 - Figure 2
Fungal forms were broad, pleomorphic, and pauciseptate. (H & E, Original magnification: 20x)
Case 2 - Figure 3
Fungal forms were associated with numerous inflammatory cells with a predominance of eosinophils. (H & E, Original magnification: 40x)
Case 2 - Figure 4
The fungal forms stained with a Periodic acid-Schiff (PAS) stain. (PAS, Original magnifications: 10x)
Case 2 - Figure 5
The fungal forms stained with a Periodic acid-Schiff (PAS) stain. (PAS, Original magnifications: 20x)
Case 2 - Figure 6
The fungal forms stained with a Periodic acid-Schiff (PAS) stain. (PAS, Original magnifications: 40x)
A 48 year old male presented with fever, weight loss, and malaise. Surgery was performed for the
clinical impression of an intestinal obstruction, and exploration of the abdomen showed an 8 cm pericecal
abscess and localized cecal ulceration.
Pathological/Microscopic Findings and any Immunohistochemical or Other Studies:
An abscess was identified in the cecal region. Microscopic examination showed granulomatous
inflammation. Localized collections of tissue eosinophilia were identified, containing foci of the
Splendore-Hoeppli phenomenon. Within these collections, broad, pleomorphic, sparsely septate fungal
forms (hyphae) could be identified. Vascular invasion was not identified. Differential Diagnoses:
Entomophthorales infection is the favored diagnostic entity. Mucormycosis is on the differential
diagnosis. Mucormycosis typically has inflammation with a predominance of neutrophils and displays foci
of vascular invasion with thrombosis; whereas basidiobolomycoiss typically has abundant eosinophilic
inflammation and a lack of vascular invasion.
Entomophthorales infection, most likely to be Basidobolomycosis, typically caused by Basidiobolomycosis ranarum
Gastrointestinal (GI) basidiobolomycosis is a relatively uncommon infection of the GI tract, typically
caused by Basidiobolus ranarum. Notable early descriptions were from the desert climates of Saudi Arabia
and Arizona, and it appears that the number of recognized cases is increasing based on an assessment of
the number of PUBMED publications per decade. The source of infection is essentially unknown; however,
it has been hypothesized that the infection is possibly acquired by ingestion of contaminated soil
(through "pica") or animal fecal material. Death may occur from intestinal perforation & abdominal
spread. Grossly, infection can produce "pseudotumors" and mimic carcinoma and can also be confused with
inflammatory bowel disease (e.g., Crohn's disease). Microscopically, infection is characterized by
granulomatous inflammation, tissue eosinophilia, tissue necrosis, and foci of the Splendore-Hoeppli
phenomenon. The Splendore-Hoeppli phenomenon refers to the deposition of amorphous, eosinophilic
material, sometimes having a hyaline-type character, around pathogenic organisms. This occurs primarily
with fungal and parasitic organisms. This phenomenon is considered to be the result of a localized
antigen-antibody reaction. Broad, sparsely septate hyphae can be identified, and the hyphal walls stain
faintly with Gomori's Methenamine Silver (GMS) or Periodic acid-Schiff (PAS) stains. Fungal infections
of the large bowel are typically considered to be rare. Histoplasma is the organism most likely to
involve the large bowel. Uncommonly, pathologists will suspect a fungal infection such as histoplasma
and will need to use silver stains to detect the organisms. Fungal infections forming masses have been
described, mimicking carcinoma. Basidiobolus ranarum belongs to the order Entomophthorales. The
Entomophthorales are an order of fungi that were previously included in the class Zygomycetes. Many
members are pathogens of insects. Entomophthorales is derived from the Greek for insect destroyer
[entomo = insect, phthor = destroyer]. Entomophthoromycosis is a rare form of zygomycosis in humans.
The 2 principal species leading to most of these infections are Conidiobolus coronatus and Basidiobolus
ranarum. It has been isolated from the soil and decaying vegetation throughout the world. Subcutaneous
disease has also been described. Definitive diagnosis requires culture of the organism. Serologic
methods employing immunodiffusion are also available.
Review of the Literature/Treatment Options (if applicable):
Patients typically undergo resection and debridement of the affected portion of the GI tract and are
treated with ≥ 3 months of antifungal therapy. The antifungal agent itraconazole has been used.
Clinical failure has been reported with amphotericin B.
Awareness of GI basidiobolomycosis is important when a fungal infection of the GI tract is
encountered. Several notable case series have been reported, particularly recently, possibly indicating
an increased incidence of the infection or at least an increased recognition of the entity.
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