An uncommon cause of allergic fungal sinusitis: Rhizopus oryzae

We report what we believe is the first case of allergic fungal rhinosinusitis (AFRS) caused by the fungus Rhizopus oryzae. Our patient was a 32-year-old woman who presented with unilateral nasal polyps and chronic nasal dysfunction. Computed tomography of the sinuses detected left-sided pansinusitis and bone erosion. T2-weighted magnetic resonance imaging demonstrated a signal void that suggested the presence of a fungal infection. The patient underwent unilateral ethmoidectomy. Histologic examination of the diseased tissue identified allergic mucin with 70% eosinophils and no fungal hyphae. Mycologic culture detected R oryzae. After a short period of improvement, the patient experienced a recurrence, which was confirmed by radiology. A second surgery was performed, and the same fungal hyphae were found in the mucus and on culture, which led us to suspect AFRS. Since no IgE test for R oryzae was available, we developed a specific immunologic assay that confirmed the presence of specific IgG, which identified a high degree of immunologic reaction against our homemade R oryzae antigens. With a long course of systemic antifungal treatment, the patient's symptoms resolved and no recurrence was noted at 5 years of follow-up.