Revision 5 for 'Calyceal diverticulum'

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Calyceal diverticulum

Calyceal diverticulum, also known as pyelocalyceal diverticulum is a congenital abnormality that results in urine filled out pouching, lined with transitional epithelium from the renal calyx or pelvis into the renal cortex. 

Epidemiology

Relatively uncommon, seen in 0.21% to 0.60% of intravenous urograms (IVU).

Risk factors include:

  • gender: females are more commonly affect than men by a ratio of 2:1 

Associations include:

  • high incidence of stone formation due to urine stagnation

Clinical presentation

The majority of the time this congenital pathology is asymptomatic and discovered when patients present for other complications such as hematuria, calculi, or repeated infections all being related to urine stasis.

Pathology

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

There are two categories of calyceal diverticulum the first and more common type communicates with a minor calyx and the second, communicates with a major calyx or the renal pelvis.

Radiographic features

Plain radiograph

Plain abdominal radiographers will often show a half moon of meniscus shaped calcification of radio-opaque milk of calcium.

Ultrasound

A calyceal diverticulum complicated by calculi or layered dependent milk of calcium appears echogenic on ultrasound

CT

Nephrographic phase contrast-enhanced CT will have an appearance 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 will be a high-attenuating material on unenhanced CT with fluid milk level.

Differential diagnosis

General imaging differential considerations include:

 

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