Case 2 -

Entomophthorales Infection, most likely to be Basidobolomycosis, typically caused by Basidiobolomycosis ranarum Alton Brad Farris, Emory University, Atlanta, GA

Click on slide thumbnail images for an enlarged view.

If you have any difficulties viewing these slides, email the webmaster.

Clinical History 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) Introduction: 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. Final Diagnosis: Entomophthorales infection, most likely to be Basidobolomycosis, typically caused by Basidiobolomycosis ranarum Case Discussion: 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. Conclusion(s): 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. References: Choonhakarn C, Inthraburan K. Concurrent subcutaneous and visceral basidiobolomycosis in a renal transplant patient. Clin Exp Dermatol. 2004 Jul;29(4):369-72. PubMed PMID: 15245532. Hussein MR, Musalam AO, Assiry MH, Eid RA, El Motawa AM, Gamel AM. Histological and ultrastructural features of gastrointestinal basidiobolomycosis. Mycol Res. 2007 Aug;111(Pt 8):926-30. PubMed PMID: 17719761. Khan ZU, Khoursheed M, Makar R, Al-Waheeb S, Al-Bader I, Al-Muzaini A, Chandy R, Mustafa AS. Basidiobolus ranarum as an etiologic agent of gastrointestinal zygomycosis. J Clin Microbiol. 2001 Jun;39(6):2360-3. PubMed PMID: 11376094; PubMed Central PMCID: PMC88148. Kradin RL. Diagnostic Pathology of Infectious Disease. Philadelphia, PA: Saunders Elsevier, 2010. Lyon GM, Smilack JD, Komatsu KK, Pasha TM, Leighton JA, Guarner J, Colby TV, Lindsley MD, Phelan M, Warnock DW, Hajjeh RA. Gastrointestinal basidiobolomycosis in Arizona: clinical and epidemiological characteristics and review of the literature. Clin Infect Dis. 2001 May 15;32(10):1448- 55. Epub 2001 Apr 20. PubMed PMID: 11317246. Mandell GL. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 7th ed. Elsevier, 2009. Mathew R, Kumaravel S, Kuruvilla S, Varghese RG, Shashikala, Srinivasan S, Mani MZ. Successful treatment of extensive basidiobolomycosis with oral itraconazole in a child. Int J Dermatol. 2005 Jul;44(7):572-5. PubMed PMID: 15985026. Nemenqani D, Yaqoob N, Khoja H, Al Saif O, Amra NK, Amr SS. Gastrointestinal basidiobolomycosis: an unusual fungal infection mimicking colon cancer. Arch Pathol Lab Med. 2009 Dec;133(12):1938-42. PubMed PMID: 19961248. van den Berk GE, Noorduyn LA, van Ketel RJ, van Leeuwen J, Bemelman WA, Prins JM. A fatal pseudo-tumour: disseminated basidiobolomycosis. BMC Infect Dis. 2006 Sep 15;6:140. PubMed PMID: 16978407; PubMed Central PMCID: PMC1574330. Yousef OM, Smilack JD, Kerr DM, Ramsey R, Rosati L, Colby TV. Gastrointestinal basidiobolomycosis. Morphologic findings in a cluster of six cases. Am J Clin Pathol. 1999 Nov;112(5):610-6. PubMed PMID: 10549247.