Jackstone: A rare entity of vesical calculus.

Jackstone calculi are urinary tract stones that have a specific appearance resembling toy jacks. They are almost always composed of calcium oxalate dihydrate consist of a dense central core and radiating spicules. They are usually light brown with dark patches and are usually described to occur in the urinary bladder and rarely in the upper urinary tract. Their appearance on plain radiographs and computed tomography in human patients has been described.

CASE REPORT

A 60-year-old patient presented in the outpatient department with chief complaints of hematuria with off and on episode of urine retention. There was history of passage of small stones in urine occasionally for last few days. On ultrasonography he was found to have 35 g prostate with slightly thickened bladder wall with a large stone in the urinary bladder. X-Ray KUB showed a large radio-opaque shadow in the pelvic region [Figure 1]. Hematological, microbiological and biochemistry examination did not reveal any abnormality. Patient underwent open cystolithotomy and large bladder stone [Figure 2] with multiple small stones were retrieved. Bladder was closed in two layers without suprapubic catheter. Patient was started on alpha blockers in the immediate postoperative period and Foley's catheter was removed on the eighth postoperative day. At follow-up of three weeks after the surgery the patient was voiding in good stream with minimal post-void residual urine.

Figure 1

Plain xray KUB showing radioopqaue shadow in the pelvis

Figure 2

Postoperative picture showing retrieved jackstone

DISCUSSION

As the name implies this variety of stone has a characteristic shape resembling a child's toy [Figure 3]. These types of stone are commonly described in the veterinary literature with common occurrence in cattle, cats and dogs. Dogs are mostly commonly affected and canine jackstones are usually composed of silica.[1]

Figure 3

Depicting child toy called jackstone

Calcium oxalate is the most common component of urinary calculi.[23] Calcium oxalate monohydrate calculi are usually smooth and black, whereas stones comprising calcium oxalate dihydrate tend to be irregular and yellow. Dihydrate stones tend to be fragmented by lithotripsy more easily than monohydrate stones. Jackstone calculi in humans are usually specific for calcium oxalate dihydrate stones.[4]

Bladder outlet obstruction remains the most common cause of bladder calculi in adults. Most common factors predisposing to bladder stone formation are—prostatic diseases, previous lower urinary tract surgery, metabolic abnormalities, upper urinary tract calculi, intravesicular foreign bodies, spinal cord injuries, transplant surgery etc.[5] Stones forming due to the above mentioned factors are usually not jackstones. The presentation of vesical calculi varies from completely asymptomatic to symptoms of suprapubic pain, dysuria, intermittency, frequency, hesitancy, nocturia, and urinary retention. Other common signs include terminal gross hematuria and sudden termination of voiding with some degree of associated pain referred to the tip of the penis, scrotum, perineum, back, or hip. The discomfort may be dull or sharp and is often aggravated by sudden movements and exercise. Assuming a supine, prone, or lateral head-down position may alleviate the pain initiated by the stone impacting the bladder neck by causing it to roll back into the bladder.

In our case the prostate is the likely cause of this stone. Enlarged prostate probably restricts the calculus into its eccentric location and contributes to the growth of stone by causing stasis of urine. It is important to recognize the characteristic shape of the jackstones as they are susceptible to lithotripsy. We did not offer lithotripsy as this modality is known to be less efficacious in case of vesical calculus.[6] We did open cystolithotomy as the intra-corporeal lithotripter malfunctioned during the procedure.