Revision 2 for 'Calyceal diverticulum'

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Calyceal diverticulum

Calyceal Diverticulum or Pyelocalyceal diverticulum is almost congenital urine-filled out pouching from renal calyx or pelvis into the renal cortex. A little percentage of cases may be acquired. It is lined with transitional epithelium.


Type 1:the more common, communicates with a minor calyx.

Type 2 : communicates with a major calyx or the renal pelvis.


A relatively uncommon , seen in 0.21% to 0.6% of intravenous urograms (IVU),but high incidence of stone formation due to urine stagnation. women more  commonly affected than men (2:1). they are found in the upper pole calyces ~50% , in the middle ~ 30% and lower poles ~20%.


The most common theory is congenital origin of diverticulum results from failure of regression of the third- and fourth-generation ureteric buds., resulting from obstructing stones or infection.

Complications are due to urine stasis:

  1. Calculi.
  2. milk of calcium.

  3. repeated infections.

Radiographic features :

Plain abdominal radiographs : +/- a half moon or meniscus-shaped calcification of radio-opaque milk of calcium.

at ultrasound ,  MRI, and non-enhanced or nephrographic phase contrast-enhanced CT: the Appearance is  similar to that of a simple cyst.The diagnosis is made with certainty in the excretory phase of imaging, the cystic structure fills with contrast material due to  communication with pelvi-calyces, and layering of contrast material is seen within.

A calyceal diverticulum complicated by calculi or layered dependent milk of calcium appears echogenic on ultrasound and  high-attenuating material on unenhanced CT with fluid milk level.

Differential diagnosis:

the following differential diagnosis have no communication with collecting system :

Renal milk of calcium cysts

 simple renal cyst


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