Renal actinomycosis mimicking renal tumor: case report.

A 68-year-old man was admitted after fever and general fatigue with severe inflammatory signs and anemia. T1- and T2-weighted magnetic resonance imaging showed low- to isointensity and low-intensity tumor in the right kidney, respectively, suggesting renal actinomycosis. However, the right kidney was explored transabdominally because the possibility of renal malignant lymphoma could not be excluded. After nephrectomy, characteristic colonies of Actinomyces were seen microscopically, and the histologic diagnosis was renal actinomycosis. The patient was treated with antibiotics and made good progress after operation. This case highlights the importance of magnetic resonance imaging for the diagnosis of renal actinomycosis.