Ileocecal basidiobolomycosis mimicking malignancy successfully treated without surgery: A case report.

BACKGROUND: Basidiobolomycosis, a fungal infection affecting immunocompetent individuals, is caused by Basidiobolus ranarum, a fungus classified under the order Entomophthorales, which was previously grouped under Zygomycetes. Gastrointestinal basidiobolomycosis (GIB) is often life-threatening, with a high mortality rate if left untreated; however, favorable outcomes have been achieved with prompt diagnosis and proper management. CASE SUMMARY: Herein, we present a case of GIB in a 32-year-old Saudi male, and smoker who presented with a 2-month history of mild-to-moderate pain in the right lower quadrant of the abdomen. On clinical suspicion of colon cancer due to the presence of an ileocecal mass on imaging studies, he underwent a colonoscopy and endoscopic biopsy followed by histopathological examination. The latter revealed colonic mucosal fragments showing ulceration, granulation tissue, and marked eosinophilic as well as mixed inflammatory cell infiltration along with scattered giant cells. A few scattered, thin-walled, broad fungal hyphae were evident on special stains. Based on the histopathological findings, the patient was diagnosed with GIB. He was started on voriconazole, but switched to posaconazole after 5 weeks because the patient developed hepatotoxicity. After about 4 months of treatment with posaconazole, he was asymptomatic, and abdominal CT revealed complete resolution of the mass lesion. CONCLUSION: This case highlights the rare presentation of GIB in an immunocompetent adult initially misdiagnosed as colon cancer, emphasizing the importance of histopathological evaluation in diagnosing fungal infections. It also underscores successful treatment with posaconazole following voriconazole-induced hepatotoxicity, demonstrating therapeutic flexibility in managing GIB.