A 73-year-old woman was referred to our department with a complaint of asymptomatic gross hematuria. Dynamic computed tomography revealed a complicated (Bosniak type IIF) cyst in the upper pole of her right kidney, which was diagnosed as a calyceal diverticulum. The diagnosis was confirmed by ureteroscopy. The diverticulum was filled with a soft protein matrix that was difficult to completely remove from the inner surface of the calyceal diverticulum. Endoscopy combined with intrarenal surgery (ECIRS) was performed to completely remove the matrix. Percutaneous nephroscopy further revealed papillary lesions on the surface of the diverticulum, confirmed as squamous cell carcinoma on pathological assessment. A laparoscopic right radical nephroureterectomy was performed, with curative intent. Pathological assessment confirmed a high-grade squamous cell carcinoma with renal parenchymal invasion (pT3). Although carcinomas in a calyceal diverticulum are highly uncommon, when present, these tend to be high-grade neoplasms that deeply invade the parenchymal wall. As the effective management of these lesions is difficult, early-stage diagnosis is required for curative treatment. We report the case of squamous cell carcinoma in a calyceal diverticulum that was difficult to diagnose on preoperative computed tomography, urinal cytology examination, and ureteroscopy but was found during ECIRS.
Carcinoma in a calyceal diverticulum is largely uncommon. Although in most previous cases, the diagnosis was established on preoperative imaging, in one of these cases, the lesion was identified during percutaneous nephrolithotripsy [
A 73-year-old woman was referred to our department with a complaint of asymptomatic gross hematuria. She had experienced a urinary tract infection and urolithiasis several years ago. On cystoscopy, we identified a gross hematuria from the right ureteral orifice. Noncontrast enhanced CT revealed a right renal stone and a complicated cyst in the upper pole of her right kidney, which was categorized as a Bosniak type IIF cyst on dynamic CT, with a maximum diameter of 58 mm (Figure
(a) Plain computed tomography image, showing a stone in the right upper urinary tract, but with no indication of the soft protein matrix in the right renal pelvis and calyceal diverticulum, which is radiolucent. (b) Dynamic computed tomography image, showing a complicated cyst, classified as a Bosniak type IIF cyst, arising from the right side of the kidney.
The renal stone was removed using flexible ureteroscopic lithotripsy. The calyceal diverticulum, which had been diagnosed preoperatively as a complicated cyst, was confirmed by ureteroscopy and retrograde pyelogram (Figure
Retrograde pyelogram image, showing a duplex collecting system in the right kidney and calyceal diverticulum connected to the upper renal calyx. Defect sign of retrograde pyelogram, caused by filling of the diverticulum by the soft protein matrix, is observable. A percutaneous nephrostomy tube in the diverticulum was placed prior to ECIRS to remove the contents completely.
We punctured the diverticulum and dilated it using a 24 Fr balloon catheter (X-Force N30 Nephrostomy Balloon Dilation Catheter; Bard, New Providence, NJ, USA), under ultrasound guidance and ureteroscopy, with a working sheath placed at the edge of the diverticular cavity. After the soft protein matrix was completely removed, papillary lesions were observed on the surface of the diverticulum using percutaneous nephroscopy (Figure
Percutaneous nephroscopic examination, showing papillary lesions in the calyceal diverticulum.
A right radical nephroureterectomy was performed using a laparoscopic approach, with curative intent. Pathological analysis confirmed a high-grade squamous cell carcinoma with renal parenchymal invasion (pT3) (Figure
Histopathological examination. (a) An area of verrucous squamous cell carcinoma, connected to a high-grade squamous cell carcinoma, identified on the inner surface of the calyceal diverticulum. (b) Under magnification, the high-grade squamous cell carcinoma was shown to invade the renal parenchyma.
Carcinoma in a calyceal diverticulum is extremely rare, with only 16 cases reported in the literature, to our knowledge. Moreover, only one case of primary squamous cell carcinoma in a calyceal diverticulum has previously been reported [
There is no consensus on the cause of calyceal diverticula. Dysfunction of the sphincters surrounding the calyces, which facilitate synchronized filling and emptying [
Calyceal diverticula often contain stones, and therefore, urolithiasis for stone removal should be performed in patients presenting with chronic pain, recurrent urinary tract infection, gross hematuria, or a decline in renal function [
In our case, pathological examination revealed a high-grade invasive squamous cell carcinoma, with squamous cell hyperplasia and verrucous carcinoma. There have been several studies on the correlation between squamous cell carcinoma and stones in the urinary tract [
In previously reported cases, the clinical diagnosis was exclusively based on preoperative imaging, with only one case identified during percutaneous nephrolithotripsy. Because in our case the diverticulum was classified as a Bosniak type IIF cyst and that the calyceal diverticulum was filled with a soft protein matrix, the diagnosis was difficult to make based on CT images and retrograde ureteroscopy. The decision to fully remove the soft protein matrix was made to prevent obstruction of the ureter and uteropelvic junction by the multiple fragments that were floating in the calyceal diverticulum, renal pelvis, and ureter. It was only after the matrix was completely removed, and the diverticular cavity was cleared that papillary lesions were observable, with a definitive diagnosis confirmed by percutaneous nephroscopic biopsy.
Naturally, seeding of carcinoma cells in the percutaneous tract during the percutaneous is of concern. However, a previous study reported a low incidence of seeding of urothelial carcinoma in the percutaneous tract, 0.3% overall and 0.75% (1/133) in the most experienced center [
In summary, we report an extremely rare case of squamous cell carcinoma in a calyceal diverticulum that was diagnosed by percutaneous nephrosopic examination. The definitive diagnosis of carcinoma in a calyceal diverticulum can be difficult to confirm by imaging, urinal cytology examination, and ureteroscopy. In our case, the diagnosis was made during the percutaneous endoscopic procedure.
The authors declare that there are no conflicts of interest.
The authors would like to thank Editage (