Actinomycosis of the urinary bladder is a rare anaerobic bacterial infection caused by Actinomyces isrealii. Initial diagnosis is often difficult and this disease is easily misdiagnosed as a urothelial or urachal tumour. The definitive diagnosis is usually made postoperatively via tissue pathology. We discuss a case of a 54-year-old male with a smoking history and a 2.5-week history of gross hematuria. Ultrasound, computed tomography and cystoscopy revealed a large inflammatory mass adherent to the right, anterior bladder wall, suggesting malignancy. Transurethral resection and histological pathology subsequently confirmed inflammatory urothelium and gram-positive bacteria consistent with actinomyces species.
IntroductionActinomycosis of the urinary bladder is a rare infection caused by the anaerobic bacteria Actinomyces isrealii. Initial diagnosis is often difficult, as it mimics urothelial or urachal tumours.1,2 The definitive diagnosis is usually made postoperatively via tissue pathology. We report a case of primary bladder actinomycosis initially diagnosed as a urothelial carcinoma that subsequently underwent a transurethral resection of a bladder tumour (TURBT). Pathologic examination subsequently confirmed actinomycosis.
Case reportA 54-year-old male presented with symptoms of 2.5 weeks of painless, gross hematuria, frequency, nocturia and hesitancy. He denied any history of irritative voiding symptoms. He has a medical history of diabetes, dyslipidemia, erectile dysfunction and a 10-pack/year smoking history. On physical exam, he had a benign abdominal and rectal exam.Follow-up ultrasound by the family physician revealed a 7.7 × 5.7 × 7.3 cm mass extending from the right bladder wall with vascularity on colour Doppler and possible extension through the bladder wall (Fig. 1). Cystoscopy showed a large bladder tumour involving the posterior wall. Urothelial carcinoma and urachal tumours were suspected at this time. The urine cytology was negative for malignant cells. A transurethral resection of the mass showed a high-grade invasive lesion macroscopically, but tissue diagnosis returned inflamed urothelial mucosa with colonies of gram positive bacteria morphologically consistent with actinomyces species (Fig. 2).Based on the pathology report, a computed tomography (CT) scan was ordered to assess for the extent of infection, inflammation and lymph node involvement. Imaging showed extensive inflammatory thickening of the bladder wall and broad-based mass on the right, anterior wall with perivesical fat involvement tracking in a cephalad direction (Fig. 3).Treatment with high-dose amoxicillin was carried out for 3 months. Follow-up CT and cystoscopy post-treatment showed residual mild inflammation and edema on the right posterior bladder wall with vast improvement over previous investigations (Fig. 4). Another 3-month regimen of amoxicillin was prescribed with instructions for follow-up imaging.
Discussion
PathophysiologyActinomycosis is a chronic infectious disease with widespread anatomical distributi...