Diagnosis of bladder diverticular tumor by transrectal biplanar ultrasonography: a case report

Abstract

Introduction:

Diverticular carcinoma of the bladder is an uncommon urological disease, and its imaging diagnosis prior to surgical intervention can be difficult.

Case presentation:

An elderly male patient was found to have an unidentified mass within the right wall diverticulum of the bladder during a physical examination. Given that the lesion was located in the posterior wall of the bladder, transrectal biplane ultrasound showed that this abnormality was bulging outwards with incomplete separation, and there was an inhomogeneous echo measuring about 8 × 9 × 13 mm. Color Doppler flow imaging detected arterial blood flow at the wide base and obscure boundary of the inhomogeneous echo. Subsequently, diverticulectomy combined with partial cystectomy was performed. Postoperative pathology and immunohistochemistry supported the diagnosis of intestinal-type adenocarcinoma.

Clinical discussion:

This case is a very rare intestinal-type adenocarcinoma arising in a bladder diverticulum. Additionally, diverticular carcinoma of the bladder is also a rare urological neoplasm that poses challenges in preoperative diagnosis. Transrectal biplane ultrasound serves as an excellent imaging modality for detecting this lesion when it is situated in the posterior wall adjacent to the rectum.

Conclusion:

Transrectal biplane ultrasound can clearly visualize the location, size, and internal characteristics of the diverticulum, as well as the blood flow of the inner lesion. This imaging technique played a pivotal role in determining the nature of the lesion and significantly contributed to the subsequent diagnosis and treatment planning.

Introduction

Bladder diverticula can be classified into congenital and acquired types. The latter is predominantly caused by bladder outlet obstruction and increased intravesical pressure, leading to a weak protrusion of the muscular layer^[1]. Prolonged urine stimulation can readily induce mucosal metaplasia within the diverticulum, which may subsequently undergo malignant transformation. The reported incidence of bladder diverticular tumors ranges from 0.8% to 10%^[2]. This case report has been reported in line with the SCARE checklist^[3].

Case report

An elderly male patient was diagnosed with abnormal imaging findings during an outpatient visit. Ultrasonography revealed an unidentified mass within the right wall diverticulum of the bladder, and noncontrast computed tomography (CT) also confirmed the presence of an abnormality. The patient was subsequently admitted for further diagnosis and treatment. After adequate counseling was done and the patient was also advised to undergo a contrast study, the patient still declined to undergo contrast-enhanced CT or magnetic resonance imaging (MRI) owing to apprehensions regarding the contrast medium. Transabdominal ultrasound demonstrated a diverticulum in the right posterior wall of the bladder with inhomogeneous echoes (Fig. 1A). Given that the lesion was located in the posterior wall of the bladder, in the far field of abdominal ultrasound, transrectal biplane ultrasound was employed to further examine the cystic pouch-like structure in the right posterior wall of the bladder. This abnormality was bulging outwards, measuring 21 × 49 × 38 mm, with incomplete separation. The width of the pouch opening was approximately 6 mm, and there was an inhomogeneous echo measuring about 8 × 9 × 13 mm. Color Doppler flow imaging detected arterial blood flow at the wide base and obscure boundary of the aforementioned inhomogeneous echo. Another loose inhomogeneous echogenic area was also observed, which could move with changes in position, measuring approximately 9 × 12 × 15 mm. Based on these findings, a malignant lesion in the bladder diverticulum with deposit formation was suspected (Fig. 1B and C). Cystoscopy revealed a papillary neoplasm within the diverticulum of the right posterior wall of the bladder. Biopsies were conducted on the surface and base of the lesion, and the samples obtained were dispatched for pathological examination, which suggested adenocarcinoma of the bladder. Subsequently, diverticulectomy combined with partial cystectomy was performed (Fig. 1D and E). Postoperative pathology showed multifocal, intestinal epithelial, heterogeneous proliferated infiltration, with morphology consistent with moderately to poorly differentiated adenocarcinoma, and immunohistochemistry supported the diagnosis of intestinal-type adenocarcinoma. During the open surgical procedure, there was no evidence of infiltration into the adjacent tissues and organs. Furthermore, the pathological findings substantiated that the excised lesion had not breached the lamina propria of the bladder diverticulum. Finally, a postoperative colonoscopy was conducted on the patient, revealing no evidence of tumors.

Figure 1.

Imaging and specimen of a bladder diverticular mass. (A) Transabdominal ultrasound shows an uneven echo in the diverticulum (at the location indicated by the measurement line). (B) Biplane ultrasound indicates a solid lesion in the diverticulum (upper measurement) and a clot (lower measurement), with blood flow visible at the wide base of the upper solid lesion. (C) Pulsed Doppler shows the arterial blood flow. (D) Cystoscopy and gross specimen after surgery display a diverticulum orifice. (E) Cystoscopy and gross specimen after operation reveal lesions in the diverticulum.

HIGHLIGHTS

• We utilized transrectal biplane ultrasound to demonstrate the location, size, and internal condition of the bladder diverticular tumor, as well as its internal blood flow.

• Transrectal biplane ultrasound played a crucial role in determining the nature of the bladder diverticular tumor prior to surgery when it is situated in the posterior wall adjacent to the rectum.

Discussion

Currently, a limited number of studies have documented the histopathological classifications of bladder diverticular carcinoma, with the predominant types being transitional cell carcinoma, squamous cell carcinoma, and adenocarcinoma. Notably, primary adenocarcinoma constitutes a mere 2% of these cases^[4]. Primary adenocarcinoma presents with a variety of morphological patterns, including intestinal-type, mucinous, signet ring cell, and mixed types^[5]. The pathological diagnosis for the case was intestinal-type adenocarcinoma, which is similar to colonic adenocarcinoma. In this particular case, the opening of the diverticulum was small, making it difficult for the cystoscope to enter. Cystoscopy requires anesthesia in the operating room. Additionally, the internal septation within the diverticulum hindered the observation of the diverticular wall. In instances where contrast-enhanced CT/MRI is unavailable, ultrasound provided valuable information regarding the location and size of the diverticular opening as well as its internal condition, which was crucial for guiding the preliminary preparation and operative process of cystoscopy^[6]. In this instance, after a transabdominal ultrasound detected the mass in the bladder diverticulum, a transrectal biplane ultrasound was employed. The higher frequency of the probe and the orthogonal display of both convex and linear arrays allowed for more accurate localization of the mass. Direct contact with the intestinal wall enabled visualization of the bladder from the posterior side, bringing the mass, originally located in the far field, closer to the probe. This facilitated the easy revelation of the base and internal blood flow of the mass, playing a pivotal role in identifying its nature. In this case, transrectal biplane ultrasound clearly demonstrated the boundary, wide base, and internal blood flow of the mass, offering a more economical and safer alternative to contrast-enhanced imaging. When malignant tumors occur, the thin wall of the bladder diverticulum is prone to infiltration and metastasis^[4]. Transabdominal ultrasound serves as the primary screening imaging modality for bladder diseases. After exploring the bladder diverticulum, it is important to observe for any abnormal echoes within it. To obtain more visual evidence regarding the mass in the lateral posterior wall, patients should be advised to undergo transrectal biplane ultrasound examination to assess whether the tumor infiltrates the diverticulum wall and to evaluate internal blood flow^[7]. Therefore, pre-operative transabdominal ultrasound combined with transrectal biplane ultrasound can provide a cost-effective and practical alternative to guide the treatment before diagnostic cystoscopy, especially in cases where contrast-enhanced CT/MRI is contraindicated, expensive, and has a long waiting time. Based on the literature review, this is the first report of transrectal biplane ultrasound applied specifically for bladder diverticular carcinoma diagnosis. Notably, cystoscopy and postoperative pathology revealed multiple lesions in this case, some of which were flattened. However, ultrasound has limitations in displaying flattened tumors, highlighting the importance of recognizing the constraints of imaging. Therefore, the combined use of cystoscopy and transrectal biplane ultrasound in certain patients may have a significant value for the accurate diagnosis of bladder diverticular tumors, which needs large studies to confirm. Additionally, we refrained from using contrast-enhanced ultrasound for the assessment of this case and did not conduct long-term follow-up after the patient’s discharge. Finally, the transrectal biplane ultrasound technology presents certain limitations, including a reliance on operator proficiency, a time-consuming process for acquiring adequate experience, patient discomfort during procedures, and the necessity for enema preparation.

Conclusion

We report a case of bladder diverticular carcinoma in an elderly male patient. Our findings indicate that transrectal biplane ultrasound plays a crucial role in visualizing the position, size, internal characteristics, and internal blood flow of the diverticulum, as well as aiding in determining the nature of the tumor.

Ethical approval

In this case report, the patient’s information was anonymized, and informed consent was obtained. This retrospective study was approved by the Institutional Review Boards of Air Force Medical Center, and the methods were carried out in accordance with the approved guidelines.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Sources of funding

No financial support was provided by any funding agency in public, commercial, or not-for-profit sectors.

Author contributions

Writing the paper: Y.Y.; data collection: L.L.; data interpretation: X.L.; data interpretation: J.X.; study design: X.F.

Conflicts of interest disclosure

The authors declare no conflict of interest.

Research registration unique identifying number (UIN)

Not applicable.

Guarantor

Xiaozhou Fan.

Provenance and peer review

Not applicable.

Data availability statement

Not applicable.