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GENITOURINARY IMAGING Table of Contents   
Year : 2004  |  Volume : 14  |  Issue : 3  |  Page : 279-281
Images : Pyelocalyceal diverticulum


Department of Radiology and Imaging and Department of Urosurgery, Vardhman Mahavir Medical College and Safdarjang hospital, New Delhi-110029, India

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Keywords: Pyelocalyceal diverticulum, Ultrasound, CT, Intravenous Urography.

How to cite this article:
Jain M, Grover S B, Kumar A, Mohanty N K. Images : Pyelocalyceal diverticulum. Indian J Radiol Imaging 2004;14:279-81

How to cite this URL:
Jain M, Grover S B, Kumar A, Mohanty N K. Images : Pyelocalyceal diverticulum. Indian J Radiol Imaging [serial online] 2004 [cited 2019 Sep 21];14:279-81. Available from: http://www.ijri.org/text.asp?2004/14/3/279/28603

   Introduction Top


Pyelocalyceal Diverticulum, also called Pyelogenic Cyst, is a urine-containing eventration of the upper collecting system, enclosed within the renal parenchyma, communicating with the main collecting system via a narrow channel, lined by non-secretory transitional cell epithileum and is surrounded by a layer of muscularis mucosae [1],[2]. Both congenital and acquired factors have been implicated in its etiology [3]. Most investigators however, believe that the congenital etiology is more likely, with these diverticulae resulting from failure of regression of the third or fourth division of the ureteric buds of the Wolffian duct [2],[4]. Pyelocalyceal diverticulae are usually asymptomatic but may present with symptoms of urinary tract obstruction when complicated by calculi or of infection, when the latter supervenes [3],[4]. Sonography and CT are non-specific and often demonstrate only a cystic mass but urographic features are characteristic and clinch the diagnosis.


   Clinical Report Top


A 42-year-old male presented with history of recurrent left renal colic. Plain radiographs had shown a single staghorn shaped calculus in the upper pole region of the left kidney. Sonography confirmed multiple coalescing calculi in the upper pole, adjoining which a simple cyst of 2.5 x 2.1 cm was observed [Figure - 1]a, b. Rest of the left kidney, right kidney and urinary bladder were normal. At Intravenous Urography, early radiographs of 5 and 10 minutes revealed a peripherally situated, spherical contrast filled cavity adjoining the upper calyceal calculus. This cavity appeared to communicate with its adjoining calyx [Figure - 2]a. The delayed radiographs at 30 minutes showed relative retention of contrast in this cavity [Figure - 2]b. CT was performed both as a non-enhanced study and after injection of intravenous contrast. The unenhanced CT showed a hypodense area of 5 HU in the left renal upper pole, which after contrast injection showed minimal enhancement with layering of contrast in its dependant portion [Figure - 3]a, b.The imaging observations were characteristic of Type I Pyelocalyceal Diverticulum in the region of upper pole of left kidney.


   Discussion Top


Patients of pyelocalyceal diverticulum are usually asymptomatic, but may complain of hematuria or have symptoms of urinary tract infection, renal colic, pyuria, hypertension or of obstruction due to calculus formation [4].

These diverticulae have been referred to variously as pyelogenic cyst, caliceal diverticula, pericaliceal cyst, congenital hydrocalicosis and pyelorenal cyst [1],[5]. The associated entities reported are vesicoureteric reflux, nephrosclerosis, sponge kidney and hypoplasia or dysplasia of the contralateral kidney [5].

The presence of a pyelocalyceal diverticulum cannot be envisaged on a plain radiograph because they are radiolucent. However, presence of an unusually mobile calculus or of milk of calcium are highly suggestive of its existence. The radiographic appearance of milk of calcium i.e. calcific semilunar density with a fluid-calcium level at the upper margin, that changes position on upright or lateral decubitus radiographs is highly characteristic [1],[2]

Pyelocalyceal diverticulum has been found in 2.1 to 4.5 per 1000 Intravenous Urographic studies [1]. On Intravenous Urography, the appearance of a pyelocalyceal diverticulum is characteristically that of a contrast filled cystic cavity, which communicates with the renal collecting system and fills with contrast medium by retrograde flow from its connecting calyx or pelvis [3]. Opacification and washout of contrast from the diverticulum may be delayed because of a slow exchange of urine between the collecting system and the diverticulum. Sometimes a pyelocalyceal diverticulum may fail to opacify during a contrast-enhanced study due to occlusion of the neck from infection, edema or scarring. Urographically, two varieties are distinguished: Type I, which is situated at the upper pole and communicates with the calyceal cup, usually at a fornix. These lesions often have a bulbous shape with a narrow connecting infundibulum. Type II diverticula communicates with the renal pelvis and may become large enough to produce mass effect. They are usually larger and rounder and the neck is short and not easily identified [3].

On Sonography, a pyelocalyceal diverticulum appears as a cystic lesion, sometimes thick-walled, arising within the renal parenchyma, which is difficult to distinguish from simple renal cyst or an obstructed hydrocalyx. However, the presence of mobile, echogenic and dependant layering due to milk of calcium is pathognomic of a pyelocalyceal diverticulum. Calculi within a calyceal diverticulum present a typical sonographic appearance of gravity-dependant echogenic structures within a cystic renal lesion, which cast posterior acoustic shadows [1].

Non-Contrast CT shows an uncomplicated, regular, fluid-filled space possibly with a thick outer wall, which may contain high attenuation mobile debris due to milk of calcium. Following contrast administration, layering of contrast in the dependant position is noted. The patency of the diverticulum is demonstrated by the gradual opacification on delayed scans [2]. Pyelocalyceal diverticulum may fail to opacify at IVU or CT if infection or scarring obstructs its infundibulum [3].

Characteristic radiographic and imaging features of a pyelocalyceal diverticulum were demonstrable in our patient who fulfilled criteria for diagnosis of a Type I variety.

Infection, hemorrhage or transitional cell carcinoma arising from its uroepithelial lining are the known complications of a pyelocalyceal diverticulum. Sealing off of the communication due to infection also has been reported to result in sealed-off abscess or cyst and rarely, xanthogranulomatous pyelonephritis [1],[2],[3].

Treatment of Diverticulum is primarily by surgical intervention to marsupalise the cavity or by partial nephrectomy, along with appropriate treatment of associated calculus and other co-existent complications.

At radiology and imaging a calyceal diverticulum must be differentiated from hydrocalix, simple cyst, parapelvic cyst, tubercular cavity and papillary necrosis. Hydrocalix refers to irregular calyceal dilatation caused by infundibular obstruction, either acquired or congenital. Hydrocalix is seen in the normal position of the calyx, whereas a pyelocalyceal diverticulum is found in the corticomedullary area. The infundibulum of a hydrocalix is usually long, while the isthmus of a pyelocalyceal diverticulum is short, so that pyelocalyceal diverticulum comes in close contact with the collecting system at some point. A simple cyst is single and unilocular, does not communicate with the pelvicalyceal system except when complicated by infection or rupture. Histological analysis may be needed for identification because simple cysts are lined by flattened cuboidal epithelium whereas pyelocalyceal diverticulum is lined by transitional epithelium. Parapelvic cysts are pyelolymphatic malformations, usually found at or near the hilum and do not communicate with the pelvis. Tubercular cavities usually present with an irregular outline, progressive increase in size and the degree of corticomedullary involvement is markedly greater than with pyelocalyceal diverticulum. Renal papillary necrosis is associated with other conditions, such as, diabetes mellitus, sickle cell anemia, etc. and the cyst or cavities are in the medullary area and represent deformed calyces [2],[5].

In conclusion, plain radiographs are nonspecific, since a pyelocalyceal diverticulum is radiolucent, unless it contains a mobile calculus or milk of calcium which also has radiographically demonstrable mobility. Similarly sonography and non contrast CT are also nonspecific and only show a simple cyst, unless milk of calcium is present. Intravenous Urography which opacifies this cystic cavity is the modality of choice for confirming the diagnosis as demonstrated in our patients.

 
   References Top

1.Wulfsohn MA. Pyelocalyceal Diverticula. J Urol 1980; 123:1-8.  Back to cited text no. 1  [PUBMED]  
2.Siegel MJ and McAlister WH. Calyceal diverticula in children: Unusual features and complications. Radiology 1979; 131: 79-82.  Back to cited text no. 2    
3.Davidson AJ, Hartman DS, Choyke PL, Wagner BJ. Davidson's Radiology of the Kidney and Genitourinary Tract. 3rd ed. Philadelphia: W.B. Saunders Company, 1999: 416-421.  Back to cited text no. 3    
4.Rathaus V, Konen O, Werner M, Feinberg MS, Grunebaum M, Zissin R. Pyelocalyceal diverticulum: The imaging spectrum with emphasis on the ultrasound features. Br J Radiol 2001; 74: 595-601.  Back to cited text no. 4    
5.Abeshouse BS, Abeshouse GA. Calyceal diverticulum: a report of sixteen cases and review of literature. Urol Int 1963; 15(6) 329-357.   Back to cited text no. 5    

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Correspondence Address:
S B Grover
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    Figures

[Figure - 1], [Figure - 2], [Figure - 3]

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