Colonic Basidiobolomycosis—An Unusual Presentation of Eosinophilic Intestinal Inflammation

We examined the epidemiology, clinical manifestations, histopathology, management, and outcomes of gastrointestinal basidiobolomycosis, an uncommon manifestation of infection caused by the fungus Basidiobolus ranarum. In this retrospective observational cohort study, cases of gastrointestinal basidiobolomycosis in the United States were identified by reviewing medical records from Mayo Clinic Hospital (Phoenix, AZ) and contacting local infectious diseases specialists, pathologists, gastroenterologists, the Arizona Department of Health Services, health departments of adjacent states, the Armed Forces Institute of Pathology, and the US Centers for Disease Control and Prevention. A comprehensive literature review identified additional cases worldwide. Of 44 patients (mean age, 37 years [range, 2-81 years]) with gastrointestinal basidiobolomycosis, most were from the United States (19 patients [43%], of whom 17 [89%] were from Arizona) or Saudi Arabia (11 [25%]). Most (28 [64%]) were previously healthy. Common chronic medical conditions among 15 patients (34%) were diabetes mellitus (8 patients [18%]) and gastric disorders (7 [16%]). Common findings were abdominal pain (37 patients [84%]) and a palpable abdominal mass (19 [43%]). Intraabdominal malignancy was the leading provisional diagnosis (19 patients [43%]). The large bowel was involved in 36 (82%), the small intestine in 16 (36%), and the liver or gallbladder in 13 (30%). Characteristic histopathologic findings were observed in 43 (98%). Eight patients (18%) died. Combined surgical intervention and antifungal therapy was the preferred treatment. Gastrointestinal basidiobolomycosis is an emerging invasive fungal infection in desert regions of the US Southwest. Clinical findings mimic malignancy and inflammatory bowel disease. Surgical excision and prolonged antifungal therapy are associated with favorable outcomes.

Basidiobolus ranarum is a known cause of subcutaneous zygomycosis. Recently, its etiologic role in gastrointestinal infections has been increasingly recognized. While the clinical presentation of the subcutaneous disease is quite characteristic and the disease is easy to diagnose, gastrointestinal basidiobolomycosis poses diagnostic difficulties; its clinical presentation is nonspecific, there are no identifiable risk factors, and all age groups are susceptible. The case of gastrointestinal basidiobolomycosis described in the present report occurred in a 41-year-old Indian male who had a history of repair of a left inguinal hernia 2 years earlier and who is native to the southern part of India, where the subcutaneous form of the disease is indigenous. Diagnosis is based on the isolation of B. ranarum from cultures of urine and demonstration of broad, sparsely septate hyphal elements in histopathologic sections of the colon, with characteristic eosinophilic infiltration and the Splendore-Hoeppli phenomenon. The titers of both immunoglobulin G (IgG) and IgM antibodies to locally produced antigen of the fungus were elevated. The patient failed to respond to 8 weeks of amphotericin B therapy, and the isolate was later found to be resistant to amphotericin B, itraconazole, fluconazole, and flucytosine but susceptible to ketoconazole and miconazole. One other noteworthy feature of the fungus was that the patient's serum showed raised levels of Th2-type cytokines (interleukins 4 and 10) and tumor necrosis factor alpha. The present report underscores the need to consider gastrointestinal basidiobolomycosis in the differential diagnosis of inflammatory bowel diseases and suggests that, perhaps, more time should be invested in developing standardized serologic reagents that can be used as part of a less invasive means of diagnosis of the disease.

Background Basidiobolomycosis is a rare disease caused by the fungus Basidiobolus ranarum, member of the class Zygomycetes, order Entomophthorales, found worldwide. Usually basidiobolomycosis is a subcutaneous infection but rarely gastrointestinal manifestations have been described; 13 adults and 10 children and a few retroperitoneal or pulmonary cases. In gastrointestinal basidiobolomycosis the colon is most frequently involved, usually presenting with subacute mild abdominal pain. In contrast to children only very few described adult patients had hepatic masses. Definitive diagnosis requires culture, serological testing can be helpful. The fungal morphology and the Splendore-Hoeppli phenomenon are characteristic histological features. There are no prominent risk factors. Usually surgery and prolonged antifungal therapy are required. Case presentation A 61 year old man presented with progressive left abdominal pain and constipation since a few months. Colonoscopy showed an obstructing tumour in the descending colon, and a hemicolectomy was performed. Histology showed inflammation, possibly caused by a fungal or parasitic infection, without definite identification of an organism. A few weeks postoperatively a CT scan made because of abdominal discomfort, revealed a livermass (6 cm). Treatment with metronidazole, directed against an amoebic liver abscess, was unsuccessful. He developed a marked eosinophilia (27.7%). A liver biopsy was performed and the patient was referred to a university hospital. A repeated CT scan showed a livermass of 9 cm diameter. Review of colon and liver biopsy samples showed extensive necrosis and histiocytes, multinucleated giant cells and numerous eosinophils. Grocott stained sections contained unusually large hyphae surrounded by strongly eosinophilic material in haematoxylin and eosin stained sections (Splendore-Hoeppli phenomenon). A presumptive diagnosis of Basidiobolus spp. infection was made and treated with amphotericin B (Itraconazol contra-indicated because of renal insufficiency). A few days later the patient died of a septic shock. After autopsy Basidiobolus ranarum was cultured from liver, gallbladder and colon. Conclusion Our patient died of gastrointestinal basidiobolomycosis with an obstructing colon tumour and a large hepatic mass. This was a rare presentation of basidiobolomycosis and the second fatal case described worldwide.