Free Research Paper On Calyceal Diverticulum

Figure 1: Abdominal US – simple renal cyst in the mid-portion of the left kidney. (Toth, 2015)
Introduction: Calyceal diverticulum is urine containing, out pouching of the calyx, into the renal parenchyma. It is a relatively uncommon and benign condition, and noticed in 0.2-0.6% of patients undergoing renal imaging. It is characterized by the cystic dilatation of a single calyx in the kidney. This dilated calyx still maintains continuity with the unaffected calyx system, through a narrow distal channel. This condition is identified incidentally during kidney imaging. Most cases of calyceal diverticulum are benign and asymptomatic and treatment is initiated only when complications arise from infection, renal calculi or rupture. (Petersen, 1992)
There are two recognized types in calyceal diverticulum: Type I and Type II. Type I lesion is the most common and it communicates with the renal calyx. In 70% of the cases the affected calyx is situated in the upper pole of the kidney. Type II lesion is much larger and communicate with the renal pelvis. It is usually seen in the inter-polar region of the kidney. Type II calyceal diverticulum is also called pyelocalyceal diverticulum. The diverticulum, is lined by a non-secretory transitional epithelium, and is filled by urine, through retrograde reflux from the calyx via the diverticulum neck. (Petersen, 1992)
Anatomy and physiology of the affected organ: Kidney is an organ of the urinary track, where blood is filtered and urine is formed. The kidney parenchyma is surrounded by a tough capsule. The renal calyces are chambers in the kidney through which urine passes. The urine formed in the neprons, first passes through the renal papillae situated at the apex, and then into the minor calyx. Minor calyses leads to the major calyx. The urine passes through the major calyx and continues into the renal pelvis and then into the ureter. Peristaltic activity of the smooth muscles that surround the calyx helps to propel the urine forward along the urinary tract. The calyceal diverticulum filled with urine and is prone to urinary stasis, which can cause secondary complications like infection, stone formation and rupture. (Older & Bassignani, 2009)
Patho-physiology of the diseases: Most cases of calyceal diverticulum are congenital. The widely held hypothesis, for its development, is the failure in the regression of 3rd or 4th division ureteric bands of the Wolffian duct. In rare circumstances, they can be acquired, secondary to an infection or stone formation. The size of the diverticulum varies from few millimeters to 7 cm, with an average of 2-3 cm. The diverticulum is prone to urinary stasis and this in turn can result in secondary complications like infection, calculi and rupture. When looking at the gross outlook of the calyceal diverticulum, it distorts the contour of the kidney, often obliterating the overlying cortex. The wall of the diverticulum is generally thin, but can become thick and fibrosed when inflammed. Histological the diverticulum is lined by the urothelial epithelium, like rest of the normal calyx. Calyceal diverticulum can be differentiated from the retention cyst, by the presence of the urothelial lining in the former. (Nakada & Pearle, 2006)
Epidemiology: The incidence of this lesion is 2.1 to 4.5 per 1000 intravenous urogram. Fifty percent of the cases have symptom of stone formation. Equal frequency of occurrence, was seen in male and females. Like wise no predilection for right or left kidney was noticed. Bilateral calyceal diverticulum was observed in 3% of the cases. Multiple calyceal diverticulums are rarely reported. Most cases (89%) of calyceal diverticulum are diagnosed in patients between 20 years to 59 years of age. (Mullett, Belfield & Vinjamuri, 2012)
Signs and symptoms: Calyceal diverticulum is usually asymptomatic and is identified during radiographic examination. When complication occurs, from infection, stone formation or rupture, the patient may present with pain, haematuria, symptomatic calculi, recurrent urinary tract infection or progressive renal damage. (Chong, Bui & Fuchs, 2000)
Diagnoses: The initial work up for the diagnosis includes urine analysis, complete blood count, basic metabolic panel and imaging of the urinary tract. The urine analysis should include microscopy and dipstick test for leukocytes, erythrocytes, proteins, nitrites and pH. Imaging techniques depend on the physician’s choice. An ultrasound can diagnose calyceal diverticulum accurately in 80% of the cases. Differential diagnosis includes renal cyst, malignancy, solitary abscess and hydrocalycosis. In general, the calyceal diverticulum is thin walled structures containing urine. In 50% of the cases, calcification in the form of milk of calcium is noticed. (Mullett, Belfield & Vinjamuri, 2012)
The imaging finding depends on the modality chosen. In a plain radiographic film, small calyceal diverticulum may be difficult to visualize. However if calcification is present, it may be visualized as hyper dense area, in the area of the kidney, similar to that seen in case of renal calculi. Renal ultrasound is commonly used in the imaging of the urinary tract. A calyceal diverticulum appears as a well defined, anechoic, thin–walled structure. The stack that helps communication between the diverticulum and healthy calyx is rarely visible. In the event of calcification, mobile hyper-echogenic structures can be seen within the cystic. A calyceal diverticulum should not exhibit Doppler’s effect. For differential diagnosis of simple cyst and malignancy, follow up imaging and surgical resection may be necessary. Renal abscess has complex internal material, with reduced acoustic transmission, in the cavity. Blood picture can also be referred to diagnose an abscess. In computed tomography the calyceal diverticulum appears as a thin walled, well defined structure, with low density. The diverticulum neck and connection can be visualized in computed tomography. The cyst may contain calcific density in the form of stone of milk or calcium. Delayed imaging using the renal neoplasm protocol, provides sufficient delay time, and may permit the diverticulum to fill in a retrograde fashion from the opacifying collecting system. (Mullett, Belfield & Vinjamuri, 2012)
Treatment: No treatment is required for asymptomatic calyceal diverticulum. Conventional approaches to treat symptomatic lesions include surgery, laparoscopy, shockwave lithotripsy, percutaneous nephrolithotomy, ureteroscopy. Surgical treatment for symptomatic lesion is geared towards obliterating the cyst cavity or its connection to the collecting system. Indications for surgery are stone formation, recurrent urinary tract infection, pain or evidence of ongoing renal damage. (Petersen, 1992)
Prognosis: With appropriate surgical management cure rates are high. Metabolic abnormalities are quite common in subjects where stone formation is noticed in calyceal diverticulum. Correction for this metabolic disturbance can help prevent remission of stone formation.
Conclusion: Calyceal diverticulum is a non secretory cavity in the renal parenchyma, lined by the transitional epithelium. The condition is usually congenital. It is rarely acquired, secondary to cortical kidney abscess or calyceal obstruction. The lesion is usually benign and incidentally detected during intravenous pyelogram. Treatment is necessary when complications arise from urinary tract infection, calculi or rupture of cyst. Fifty percent of the calyceal diverticulum cases have calculi. Mobile calculi are common feature in calyceal diverticulum. The etiology of calculi, are urinary stasis and an underlying metabolic disorder. It is very challenging to treat this condition and surgery is often necessary. Pain in the lower lumbar, haematuria, recurrent urinary tract infection, nephrolithiasis and cystic mass in imaging are the often noticed signs and symptoms. The condition can be diagnosed by ultrasound, intravenous urography or CT scan. The diagnosis can be confirmed, only by the excretory phase of DT scan or MRI. Differential diagnosis is simple cyst, malignancies, and abscess. The condition is treated by open or laparoscopic surgery. The technique is called partial nephrectomy, which involves removal of diverticulum with the surrounding renal parenchyma. Endoscopic therapy involves percutaneous access to the diverticulum, to remove the calculi. The connection to the diverticulum to the adjacent calyx is extended, in order to prevent urinary stasis. The prognosis is usually good, when treated promptly. Correcting the underlying cause for metabolic abnormality can prevent relapse of the calculi.

References:

Chong, T., Bui, M., & Fuchs, G. (2000). CALYCEAL DIVERTICULA. Urologic Clinics Of North America,27(4), 647-654. doi:10.1016/s0094-0143(05)70114-2
Mullett, R., Belfield, J., & Vinjamuri, S. (2012). Calyceal Diverticulum - a Mimic of Different Pathologies on Multiple Imaging Modalities. Radiology Case, 6(9). doi:10.3941/jrcr.v6i9.1123
Nakada, S., & Pearle, M. (2006). Advanced endourology (pp. 124-127). Totowa, N.J.: Humana Press.
Older, R., & Bassignani, M. (2009). Teaching atlas of urologic imaging (pp. 27-30). New York: Thieme.
Petersen, R. (1992). Urologic pathology (pp. 134-136). Philadelphia: Lippincott.
Stunell, H., Mcneill, G., Browne, R., Grainger, R., & Torreggiani, W. (2010). The imaging appearances of calyceal diverticula complicated by uroliathasis. BJR, 83(994), 888-894. doi:10.1259/bjr/22591022
Toth, K. (2015). Calyceal Diverticulum of the Kidney – Diagnostic Imaging Dilemma in Pediatric Patients – Case Report. Pol J Radiol, 80, 27-30. doi:10.12659/pjr.892053