C-194. Primary Renal Zygomycotic Infarction Mimicking Renal Neoplasia in an Immunocompetent Patient

S. Goel, J. E. Carter, M. Culpepper, A. G. Kahn;
Univ. of South Alabama, Mobile, AL.

Isolated renal infections with fungal organisms of the Class Zygomycetes are rare and are most frequently seen in patients who are immunocompromised due to human immunodeficiency virus infection, diabetes mellitus, organ transplantation, or chemotherapy. These infections are frequently fatal with mortality rates greater than 50% reported in small series of cases. The zygomycotic organisms have a propensity for angioinvasion, and infections may present clinically as massive infarction mimicking neoplasm on imaging studies. We report the case of a 45-year-old African-American male who presented with symptoms of right-sided pyelonephritis including fever, nausea, and flank pain. The patient’s medical history was significant only for sickle cell trait, and no evidence of immunosuppression was identified. Renal ultrasound imaging revealed a hypoechoic lesion in the superior pole of the right kidney, and the radiologic differential diagnosis included neoplasm, abscess, and infarct. Urine cultures were negative, but urinalysis showed white blood cells which were too numerous to count. The patient's fever initially resolved after antibiotic therapy but eventually recurred. A computed tomography scan of the abdomen and pelvis performed two weeks after the initial presentation showed no change in the renal mass, and a right nephrectomy was subsequently performed. Upon gross sectioning, an 8.5 cm well-circumscribed lesion was identified in the upper pole of the kidney. Microscopic sections showed extensive necrosis of the renal parenchyma and large, broad, aseptate fungal hyphae with irregular branching. Angioinvasion by the fungal hyphae with associated thrombosis was seen. The morphologic features of the organism were most compatible with a Zygomycete. No evidence of disseminated fungal disease was identified on imaging studies. Post-nephrectomy treatment with amphotericin B resulted in the resolution of symptoms. This case represents a successful outcome of a rarely reported isolated renal zygomycosis in a patient with no known underlying risk factors for the infection and illustrates the wide range of clinical presentations with which zygomycotic infections may present.