Renal Actinomycosis, A Rare Diagnosis Which Can Clinically Mimic a Malignancy, Case Report and Review of the Literature

[Introduction]Actinomycosis is an unusual infection, which usually appears in the thoracic, cervicofacial, and abdominal areas. Renal actinomycosis is rare and has not yet been reported in children.[Case Presentation]An 8-year-old boy presented with a fever, weight loss, and flank pain two weeks after a sore throat. As the imaging studies were in favor of the malignant tumor of the right kidney, he underwent right radical nephrectomy. Pathologic study revealed Xanthogranulomatous pyelonephritis and actinomyces bacterial colonies.[Conclusion]Renal actinomycosis is difficult to diagnose due to its non-specific clinical findings and near similarity to other inflammatory and tumoral conditions. Early diagnosis is important for medical treatment and decrease of un-necessary surgery. Using auxiliary diagnostic methods can be helpful in this aspect. Percutaneous core needle biopsy or fine needle aspiration possesses higher accuracy and specificity in comparison with other methods.