A rare presentation of alkaptonuria: Extensive prostatic calculi with highlight of stones found in a unique paraprostatic urethral diverticulum

Abstract

Introduction: We present a case of Alkaptonuria (AKU) presented with severe lower urinary tract symptoms (LUTS) secondary to extensive prostatic calculi deposited in the para prostatic diverticulum. Prostatic calculi are seen in chronic prostatitis, chronic pelvic pain syndrome and benign prostate hyperplasia; however, in patients with AKU, prostatic calculi and/or calcifications are more extensive. A para prostatic diverticulum is a rare entity in males; however, it should be considered in patients with AKU based on this case report.

Diagnosis, therapeutic interventions, and outcomes: A patient with AKU presented with extensive prostatic calculi that were deposited in para prostatic diverticulum, urethra and urinary bladder. The stones were successfully managed endoscopically.

Discussion: Paraprostatic diverticula or urethral diverticula are rare entities. They may be congenital or acquired due to recurrent Urinary Tract Infections (UTIs) or distal urethral obstruction. The distal obstruction of the urethra secondary to stones was the most likely etiology of the paraprostatic diverticulum in our case. The possible mechanisms behind stone formation in our case were chronic stasis and urinary infection within a urethral diverticulum proximal to the urethral obstruction.

Conclusion: This case sums a rare case of AKU and paraprostatic diverticular stones; in addition, it highlights the role endoscopic management of prostatolithiasis in AKU patient.

Keywords: Alkaptonuria; Case report; Paraprostatic urethral diverticulum; Prostatic calculus; Prostatolithiasis; Transurethral a pneumatic lithotripter.

Fig. 1

Supine KUB (A) showing numerous radiopaque stones at the projection of urinary bladder and prostate, note also advanced changes of alkaptonuria seen in spine, pre-operation non-contrast urinary tract CT (B + C) showing multiple stones in the urinary bladder and prostate.

Fig. 2

Post operation non-contrast urinary tract CT (A + B) showing only few residual stones, the largest on the right side of the prostate and pelvic MRI coronal STIR (C) showing fluid filled diverticulum in the left lateral aspect of the prostate (arrow), axial T2 (D) showing the prostatic diverticulum containing tiny hypointense stone (arrow).

Fig. 3

Axial non-contrast urinary tract CT (A + B) show near completely removal of all stones (residual tiny stone in the prostate, arrow).