Calyceal diverticulum simulating a renal tumor

Calyceal diverticulum (CD) is a rare anatomic anomaly with an incidence of 0.2% to 0.6% in the patients undergoing renal imaging. They are considered benign lesions and malignancy is exceedingly rare. For diagnosis it is suggested to perform a multiphasic contrast-enhanced computed tomography (CT) evidencing a diverticulum of the pelvicalyceal system with thin-walled cavities communicating with the central collecting system. However, they can be usually mistaken as kidney cancers leading to unjustified nephrectomy. Here, we present a case of a 34-year-old patient who underwent surgery in 2022 due to suspected kidney cancer and histopathological analysis surprisingly reported a CD.

[Retrograde intrarenal surgery for kidney diseases]

INTRODUCTION

Retrograde intrarenal surgery (RIRS) is being actively implemented in the treatment of renal stones and other diseases. If necessary, RIRS can be combined with percutaneous procedures.

AIM

To study the results of RIRS in patients with nephrolithiasis and various renal disorders.

MATERIALS AND METHODS

A total of 106 patients who undergone RIRS were included in the study. There were 66 men (63.4%) and 40 women (36.6%). Mean age was 46.8+/-15.6 years. The indication for RIRS in 84 (79.2%) patients was renal stones. Calculus in calyceal diverticulum were diagnosed in 6 (5.7%), encrusted stents in 8 (7.7%), urinary fistulas after partial nephrectomy in 5 (4.7%), pelvis tumors in 2 (1.9%), pelvis perforation after marsupialization of parapelvic cyst in 1 (0.9%) patient, respectively. Simultaneous retro- and antegrade procedures were performed in 27 (25.5%) cases. In those with nephrolithiasis and encrusted stents, lithotripsy was done with the removal of stone fragments. Two patients underwent endoscopic resection of the pelvis tumor. In six patients, the neck of the diverticulum was incised after lithotripsy, while in five cases retrograde endoscopically controlled percutaneous treatment urinary fistulae was performed. In one case, laser fulguration of the pelvis defect with stenting was done.

RESULTS

RIRS was effective in 72 (85.7%) of 84 patients with renal stones. The operation time was 70.8+/-10.2 minutes. In 12 (14.3%) cases with residual fragments, extracorporeal shock-wave lithotripsy (n=7) and repeated RIRS (n=5) were performed. The efficiency of RIRS after two sessions was 91.7%. Complications were observed in 11 (10.4%) patients. With encrusted stents, the operation time was 95.0+/-16.5 min. After laser fragmentation of encrustations in the lower part of the stent, percutaneous lithotripsy was performed with antegrade removal of its upper half. The time for RIRS in those with diverticula was 60.0+/-8.5 min, the average stone size was 8 mm (from 6 to 10 mm). In all cases lithotripsy with mucosal fulguration was successfully done. The procedures for urinary fistulae were also effective (operation time was 45.0 +/- 20.5 minutes) and there were no complications.

CONCLUSION

RIRS is a safe and effective treatment for patients with nephrolithiasis and other kidney disorders. Modern flexible ureteroscopes allows to examine the collecting system and to perform lithotripsy and removal of stone fragments.

A Case Report of Calyceal Diverticulum: Differential Diagnosis for Organ-Preserving Operations

Calyceal diverticula and epidermal cysts are extremely rare kidney lesions with unknown etiology and pathogenesis. They have non-specific clinical and radiological picture. Despite the benign nature, sometimes these disorders mimic malignant tumors leading to unjustified nephrectomy. We present a clinical and morphological observation of a multicystic lesion in a 76-year-old patient's right kidney filled with keratinized masses and imitating a malignant solid tumor. The detailed gross, histological and immunohistochemical (desmin, cytokeratin 7, uroplakin and p63) analyses of the kidney tissue excluded the malignant nature of the lesion. The final differential diagnosis was between an epidermal cyst and calyceal diverticulum with pronounced squamous cell metaplasia of urothelium. The upper pole localization of the lesion, its connection with the pelvicalyceal system through the unobstructed isthmus, the presence of urothelial lining and smooth muscle cells in its wall let us diagnose a calyceal diverticulum type I. Knowledge of the key clinical and morphological features of epidermal cysts and diverticula of the pelvicalyceal system will help the practicing physicians suspect the benign nature of such lesions and perform organ-preserving operations.

Differentiation of simple renal parenchymal cyst and calyceal diverticulum

BACKGROUND

Calyceal diverticulum is the cystic eventration of the upper urinary tract within the renal parenchyma, which gives the first impression of a simple renal cyst and therefore can easily be misdiagnosed. We conducted a study to assess the role of static-fluid magnetic resonance (MR) urography in the differentiation of renal parenchymal cysts and calyceal diverticulum in comparison with focused renal ultrasonography (US).

METHODS

Focused renal US, static-fluid, and excretory MR urography studies of 45 children who were admitted to our pediatric nephrology department with a diagnosis of renal cyst were reviewed retrospectively. Excretory MR urography was accepted as gold standard for the diagnosis of calyceal diverticulum. Sensitivity and specificity of focused renal US and static fluid MR urography in the diagnosis of renal calyceal diverticulum were assessed. Interobserver agreement between three radiologists in the diagnosis of calyceal diverticulum on MRI was also evaluated.

RESULTS

The study included 29 patients (13 boys and 16 girls) aged between 6-18 years (mean 11.5 ± 4.1). Five calyceal diverticula and 24 solitary renal parenchymal cysts were diagnosed. The sensitivity and the specificity of focused renal US were 40% and 100% in the diagnosis of calyceal diverticulum. The sensitivity and the specificity of static-fluid MR urography were 100% and 91.6%, respectively. The degree of interobserver agreement was excellent for the diagnosis of diverticulum for static-fluid MR urography (κ = 0.86, 95% CI: 0.71-1.00).

CONCLUSIONS

Static-fluid MR urography can be successfully used in children for the differentiation of renal parenchymal cyst and calyceal diverticulum due to its high sensitivity and specificity, without exposing children to ionizing radiation or intravenous contrast agents.

[Giant stone complicating calyceal diverticulum]

Calyceal diverticulum is acystic cavity in the renal parenchyma, communicating with the collecting system via an infundibulum. In more than 40% of cases it is associated with a stone and in most cases appears as milk of calcium forming a fluid level or multiple small stones. We here report the case of an 82-year old patient with no previous history, presenting with mild and intermittent right flank pain lasting for 8 years. Clinical examination was normal. The patient first underwent X-ray of urinary tree without preparation showing a density of calcium projecting into the upper pole of the right kidney (A). The patient then underwent uroscanner showing giant stone measuring 28mm within a caliciel diverticulum of the upper pole directly communicating with the renal pelvis (B). No associated urinary tract infection or haematuria were detected. Given patient's age and that he was paucisymptomatic and uninfected, therapeutic abstention and monitoring were indicated. In accordance with the recommendations of the experts, only symptomatic intradiverticular stones must be treated. First, extracorporeal shockwave lithotripsy (ESWL) allows improvement to the symptoms in 1 patient out of 2 and no stone fragmentation in 1 patient out of 4. In second intention, flexible uretero-renoscopy should be performed. Percutaneous nephrolithotomy can be performed if the stone is located in the lower pole (rare). Finally, in case of failure, laparoscopic treatment or open surgery may be proposed.

Difficulties with access in percutaneous renal surgery

Percutaneous renal surgery provides a minimally invasive approach to the kidney for stone extraction in a number of different clinical scenarios. Certain clinical cases present inherent challenges to percutaneous access to the kidney. Herein, we present scenarios in which obtaining and/or maintaining percutaneous access is difficult along with techniques to overcome the challenges commonly encountered. Also, complications associated with these challenging percutaneous renal surgeries are discussed.