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Calyceal Diverticulum

Definition

A calyceal diverticulum is a renal cystic cavity. It is lined with urothelium and has (or had) a connection to a pyelocalyceal system. Synonym: pyelogenic cyst.

Epidemiology of calyceal diverticula:

4,5:1000 (from studies with intravenous urography)

Etiology of Calyceal Diverticula

Congenital:

Result of failed degeneration of ureteric bud branches.

Acquired:

Calyceal diverticula may develop from a cortical kidney abscess, a cortical cyst, or from calyceal obstruction. Complications of urinary stasis are recurrent urinary tract infections, milk of calcium, or nephrolithiasis.

Signs and Symptoms of Calyceal Diverticula

• Pain, hematuria, or recurrent infections
• Nephrolithiasis
• Cystic mass in imaging

Diagnostic Workup

Renal sonography:

Renal ultrasound reveals a cystic structure near a calyx, often filled with echogenic content (milk of calcium, changing with the position of the examination).

CT:

Best imaging procedure for the diagnosis of unclear renal cysts [fig. Calyceal diverticulum in CT].

Intravenous Urography:

Caliceal diverticula are often visible on the plain KUB abdominal X-ray (milk of calcium). Otherwise, the calyceal diverticulum presents as a mass, pooling of contrast media is only sometimes visible within a few minutes. Late films after 1–3 hours are helpful.

Calyceal diverticulum: the CT scan shows the filling of the cystic mass with contrast media. With kind permission, Dr. G. Antes, Kempten.

Retrograde pyelography:

Perform retrograde pyelography before treatment of nephrolithiasis or during invasive diagnostic workup of hematuria [fig. Calyceal diverticulum in retrograde pyelography].

Retrograde pyelography of a calyceal diverticulum on the right side. Invasive imaging was indicated for single-sided hematuria. Some clots lead to filling defects of the contrast media in the calyceal diverticulum. With kind permission, Dr. F. Schmidt, Augsburg.

Diagnostic Puncture:

The creatinine concentration of the aspirated fluid is significantly higher than the serum creatinine concentration. A cytological examination is an option to exclude a malignant cyst.

Differential Diagnosis:

Treatment of Calyceal Diverticula

Endoscopic Therapy:

First, obtain percutaneous access into the calyceal diverticulum and remove calyceal stones, if present. Consider fulguration of the diverticular mucosa to induce shrinkage. Dilate the connection between the diverticulum and calyx to secure urine drainage. Place a thick nephrostomy into the renal pelvis.

Open or Laparoscopic Surgery:

Partial nephrectomy: removal of the diverticulum with corresponding renal parenchyma.

References

Waingankar, N., Hayek, S., Smith, A. D., and Okeke, Z. (2014). Calyceal Diverticula: A Comprehensive Review. Reviews in Urology, 16(1), 29-43. https://doi.org/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4004282/

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