Brunn's Cyst Inducing Persistent Lower Urinary Tract Symptoms in a Young Man: A Case Report

Abstract

Background: Lower urinary tract symptoms (LUTS) are mostly caused by hyperplasia of the prostate in the elderly generation or are the consequence of a urethral stricture in young men. Proliferated Brunn's cell nests forming cysts at the bladder neck can likewise result in similar symptoms and can, therefore, often be overlooked.

Case Presentation: The case describes a 46-year-old man presenting with the typical LUTS of urgency and pathologic residual urine volume of 350 mL. Sonographic and cystoscopic diagnostics showed a cystic lesion located at the bladder neck, acting as a ball valve mechanism. Transurethral deroofing and resection of the cyst resulted in an immediate resolution of LUTS and a symptom-free patient with no residual urine at follow-up.

Conclusion: The presence of a Brunn's cyst is rare but should be kept in mind as a differential diagnosis of LUTS in young men.

Introduction

The literature describes cysts developing out of Brunn's cell nests as a rare cause of bladder outlet obstruction symptoms in young, otherwise healthy, men. These primarily benign proliferating cell nests formations¹ can cause a valve mechanism when located in the bladder neck and formed to cysts, leading to irritating voiding symptoms and increased postvoid urine volume.

Presentation of Case

We report a case of a 46-year-old Caucasian man, who was referred to our department with gradually increasing symptoms of urinary urgency, frequency, and hesitancy summarized as lower urinary tract symptoms (LUTS). Postvoid residual volume was repeatedly increased up to 350 mL. The patient had no relevant past medical history and was not taking any medication. He was a nonsmoker, drank alcohol only occasionally, and did not use recreational drugs. Physical, including digital rectal, examination showed no abnormal findings. Urine cultures were always negative; previous empiric antibiotic regimes showed no symptom improvement, and spasmolytic medication had also no effect. Uroflowmetry confirmed a low maximum flow rate (Qmax) of 7 mL/s, prolonged voiding time >60 seconds with a typical plateau curve. Transrectally measured prostate volume was 35 mL (Fig. 1). Ultrasonography revealed no signs of hydronephrosis or dilated ureter and no renal abnormality (no duplicated collecting system), but an isolated cystic lesion of 1.51 × 1.48 × 1.88 cm was seen in the area of the bladder neck with no connection to the ureteral orifices, above the prostate surrounded by a 1.2 × 1.25 × 1.28 hyperechoic node complex with small cystic formations showing low vascularization and hardening on elastography (Fig. 1).

FIG. 1.

Transrectal ultrasonography images showing a 1.51 × 1.48 × 1.88 cm cystic lesion in the bladder neck region, above the prostate and separate from the ureterovesical junctions, with no connection to the ureteral orifices (A) surrounded by a 1.2 × 1.25 × 1.28 hyperechoic node complex with small cystic formations (B) showing low vascularization and hardening on elastography (C). The prostate volume was 35 mL (D).

Cystoscopy was then carried out under general anesthetic in the lithotomy position for further evaluation using a 26F resectoscope, confirming the presence of an isolated cyst lying within the bladder neck at 12 o'clock, which seemed to be acting as a valve during micturition (Fig. 2). An intravesical ureterocele was excluded as the cyst was not thin walled surrounding the ureteral orifice. As an ectopic ureterocele is mostly associated with a duplicated collecting system as the result of abnormal embryogenesis, we also excluded it as a possible differential diagnosis. Endoscopic appearance did not indicate the presence of a malignancy and no pathologic findings intravesically. The prostatic and penile urethra showed also no abnormalities. Transurethral unroofing and bipolar continuous flow transurethral resection of the cyst and the bladder neck was subsequently carried out (Fig. 2). The surgical procedure was well tolerated, there was no macrohematuria at any point of time and the 20F three-way urethral Foley catheter that had been inserted intraoperatively could be removed on the second postoperative day. Histologic examination showed nests of altered benign uroepithelial cells with cystic structure, compatible with the presence of a Brunn's cyst. The patient was symptom free after postoperative removal of the catheter and remained so at follow-up with no postvoid residual volume.

FIG. 2.

Cystoscopic view of the cystic lesion and the consecutive bladder outlet obstruction (A–C). The cyst had no connection to the ureteral orifices. Endoscopic result after transurethral deroofing and resection of the Brunn's cyst (D–F).

Discussion and Literature Review

LUTS such as described in this case are usually caused by enlargement of the prostate or, in younger men, also by urethral strictures. Our patient had a rare cause of benign urinary obstruction caused by a Brunn's cyst of the bladder neck, of which only three cases have previously been reported in literature,^2,3 describing the first case in the year 1988.⁴ In this as in all reported cases, LUTS have disappeared immediately after transurethral resection of the cyst. Prostate cysts are the most likely differential diagnosis, even though these formations arise intraparenchymal or from structures such as the ejaculatory duct.⁵ The further differential diagnosis of an intravesical ureterocele can usually be differentiated from obstructing Brunn's cysts because they are thin walled directly surrounding the ureteral orifice. Moreover, the more frequently occurring “ectopic” ureterocele, located at the bladder neck, can be excluded as this type of ureterocele is mostly associated with a complete renal duplication. Brunn's nests are thought to be clusters of cells derived from urothelium cells, which become displaced, proliferate, and then form cysts.⁶ Moreover, there is association with other types of proliferative processes such as cystitis cystica and cystitis glandularis.⁷

A report described formation of this type of cell cluster in 9 out of a total of 100 histologic specimens taken at cystoscopy, of which one was malignant.⁸ Franco et al. have considered the development of Brunn's cysts to be based on congenital predisposition.⁴ The similarity of Brunn's nests to histologically large nested urothelial cancer has been described in the past,⁹ emphasizing awareness to precise histopathologic staging after resection. It remains open to question why these cysts have yet never been reported in female patients. In summary, focused sonographic evaluation should be performed when LUTS persist after ruling out the classical diagnosis for the complaint, so that a causal therapy can be offered.

Conclusion

The presence of a Brunn's cyst at the bladder neck, although rare, should be borne in mind when young, otherwise healthy, patients present with persistent LUTS.

Abbreviation Used

LUTS

lower urinary tract symptoms

Authors' Contributions

W.H. performed endoscopic surgery. F.A. contributed radiologic imaging. A.K.L., G.S., and R.P. conceived and designed the report, performed the patient record review, and drafted the article. All authors made substantial contributions to the article draft and critically revised it. All authors approved the submitted and final versions.

Disclosure Statement

No competing financial interests exist.

Cite this article as: Lindner AK, Schachtner G, Aigner F, Biggel S, Horninger W, Pichler R (2019) Brunn's cyst inducing persistent lower urinary tract symptoms in a young man: a case report, Journal of Endourology Case Reports 5:4, 171–173, DOI: 10.1089/cren.2019.0065.