[Renal actinomycosis with fistulized lumbar abscess]

The authors report a case of renal actinomycosis in an adolescent presenting with two fistulized lumbar abscesses. This rare disease, which generally has a good prognosis, is difficult to diagnose, both clinically and radiologically. The positive diagnosis is based on histological examination, more frequently of the nephrectomy operative specimen, than ultrasound-guided fine needle aspiration biopsy of an atypical renal tumour. Conservative treatment with high-dose penicillin gives excellent results.