Villous adenoma of the urinary bladder with imaging findings suggestive of enterovesical fistula: A case report

Abstract

Villous adenomas of the urinary bladder are rare epithelial neoplasms with malignant transformation potential, exhibiting histological features similar to their gastrointestinal counterparts. Their low prevalence has hindered clinical characterization and differential diagnosis from other malignant bladder entities. We present the case of a 63-year-old woman with a history of cardiovascular and metabolic diseases who was admitted for acute urinary obstruction and hematuria. Imaging studies revealed a bladder mass and imaging findings suggestive of a possible enterovesical fistula, although no direct evidence was identified. Cystoscopy identified a 6 cm vegetative lesion in the bladder trigone, which was completely resected trans-urethrally. Histopathological and immunohistochemical analyses confirmed the diagnosis of villous adenoma of the bladder, with positive staining for CK-20 and CDX-2. The patient had a favorable postoperative course. Although rare, villous adenoma of the bladder should be recognized due to its malignant potential and the need for close postoperative surveillance. This case report contributes to the growing body of knowledge regarding this entity in female patients.

Introduction

Villous adenomas are rare lesions with a significant potential for malignant transformation due to their histological and pathophysiological features. While these neoplasms are well recognized in the gastrointestinal tract, their occurrence in the urinary tract is uncommon. Reported cases of villous adenomas of the bladder remain scarce, limiting the epidemiological characterization of this entity [1].

Histologically, these lesions are composed of villous structures lined by columnar epithelium, with variable presence of mucin-secreting goblet cells. Their immunohistochemical profile typically includes positivity for carcinoembryonic antigen (CEA), cytokeratin 20 (CK-20), and CDX-2, while they are generally negative for epithelial membrane antigen (EMA) [2,3]. The literature indicates a higher prevalence in male patients, usually presenting after the age of 60 [1]. This report describes a case of villous adenoma of the bladder in a 63-year-old woman, emphasizing the importance of the differential diagnosis of this rare neoplasm as well as its surgical management.

Case report

A 63-year-old married female physician with no history of occupational exposure to carcinogens presented to the emergency department in January 2023 with acute urinary obstruction. Her past medical history included type 2 diabetes mellitus diagnosed 9 years prior, managed with metformin; hypertension controlled with losartan; rheumatic valvulopathy and chronic heart failure of 25 years’ duration, with mitral and aortic valve replacement at the age of 33; and a benign breast biopsy at age 54.

She reported previous episodes of hematuria with amorphous clots in the preceding 2 weeks. On physical examination, the patient was neurologically intact, with a palpable multinodular thyroid, a midsystolic murmur at the aortic focus with cervical radiation, a globose abdomen due to adiposity, no peritoneal irritation signs, and external genitalia consistent with her age and sex.

Transurethral Foley catheterization revealed the passage of filiform and amorphous clots mixed with bloody mucus. Laboratory results showed hemoglobin of 10.3 g/dL, hematocrit of 30.9%, and leukocytosis (18.23 K/uL). Bladder ultrasonography (USG) demonstrated a heterogeneous mass with power Doppler enhancement (Fig. 1A). Colonoscopy revealed diverticula in the descending colon without abnormalities of the rectal ampulla. Computed tomography (CT) of the abdomen showed a heterogeneous mass with variable density and the presence of intravesical air, raising suspicion of a possible enterovesical fistula; however, this finding was interpreted with caution given that the CT was performed after Foley catheter placement (Fig. 1B).

Fig. 1.

(A) Bladder ultrasound showing a heterogeneous mass with power Doppler enhancement. (B) Noncontrast abdominal CT, axial view, demonstrating intravesical air.

Based on these findings, a presumptive diagnosis of enterovesical fistula was made. Anticoagulation therapy was withheld, and bridging therapy with parenteral heparin was initiated. Cystoscopy revealed abundant clots and mucus, as well as a 6-cm vegetative lesion in the bladder trigone and lateral walls, with necrotic tumor material (Fig. 2).

Fig. 2.

Cystoscopy and biopsy. (A) Irregular papillary lesion with a broad base in the bladder dome. (B) Bladder neck with mucoid tissue and amorphous clots of variable size. (C) Bladder base with mucoid tissue. (D) Trigone with mucoid tissue.

Both ureteral orifices were patent, and no abnormalities were observed in the posterior bladder neck. Complete transurethral resection of the lesion was performed, followed by placement of a 3-way Foley catheter.

The resected specimen consisted of multiple tissue fragments measuring approximately 7 × 5 cm, with an irregular surface, light brown coloration, and soft consistency. Histopathological examination revealed a glandular/mucinous villous epithelial neoplasm characterized by digitiform projections lined by tall columnar cells with elongated nuclei and atypia, consistent with villous adenoma (Fig. 3).

Fig. 3.

Histopathology of villous adenoma. A glandular/mucinous villous epithelial neoplasm with digitiform projections lined by tall columnar cells with elongated nuclei and atypia.

Immunohistochemical analysis confirmed the diagnosis, demonstrating positivity for CK-20 (Fig. 4A) and CDX-2 (Fig. 4B). The patient had a favorable postoperative course.

Fig. 4.

Immunohistochemistry. (A) CK-20 positive staining. (B) CDX-2 positive staining.

Discussion

Villous adenomas of the urinary tract are glandular neoplasms with histological and immunohistochemical similarities to their gastrointestinal counterparts and may act as precursors to invasive adenocarcinoma. Affected patients commonly present with hematuria, irritative voiding symptoms, and mucosuria, a clinical profile that overlaps with colonic-type adenocarcinoma of the bladder, secondary extension of colonic adenocarcinoma, and papillary urothelial carcinoma with villo-glandular differentiation. These lesions may arise in various locations, including the urachus, bladder dome, trigone, urethra, renal pelvis, and ureter [4].

Villous adenoma lacks specific imaging features on ultrasound, CT, MRI, or cystoscopy that allow reliable preoperative differentiation from other bladder neoplasms. In contrast, bladder fistulas may be detected radiologically; however, in this case, only indirect signs of bladder fistulas such as intravesical air and diverticula were observed [5,6].

It is important to note that the presence of intravesical air is not specific for enterovesical fistula and may be observed in other conditions, including recent bladder instrumentation, catheterization, or emphysematous cystitis [7,8]. In the present case, CT imaging was performed after Foley catheter placement, which represents a potential source of intravesical air. Therefore, the diagnosis of enterovesical fistula could not be confirmed and should be interpreted as a radiologic suspicion rather than a definitive finding.

The pathogenesis of villous adenomas of the urinary tract is thought to be embryologic, since the colon, rectum, urethra, and bladder derive from cloacal tissue, accounting for the morphological and cytogenetic similarities across both systems [4]. Three published cases have reported the coexistence of bladder fistulas and villous adenomas, suggesting a possible association between these entities [[9], [10], [11]]. It has been hypothesized that villous adenomas of the bladder may arise secondarily to vesical fistulas, based on studies indicating that appendico-vesical fistulas following appendicitis may present with pneumaturia and recurrent urinary tract infections. A case of appendico-vesical fistula caused by an appendiceal papillary villous adenoma has also been reported [9].

These neoplasms are more frequent in men, which has been attributed to higher exposure to carcinogens such as tobacco and occupational chemicals, as well as hormonal factors, given that estrogens may exert a protective effect against chronic urothelial changes in women [12]. Consequently, reported cases in women remain rare. To date, fewer than 20 cases of villous adenoma of the bladder in women have been described, most often presenting with gross hematuria and irritative bladder symptoms, usually with unremarkable urinalysis results, complicating diagnosis [1].

Despite the diagnostic challenges in distinguishing villous adenoma from bladder adenocarcinoma, villous adenoma generally carries a favorable prognosis following surgical excision. Nevertheless, given the potential for malignant transformation, periodic cystoscopic surveillance is recommended. Although no standardized follow-up protocol exists due to the rarity of this entity, we suggest regular cystoscopic evaluation, particularly in the first years after resection.

Cross-sectional imaging plays a key role in the initial assessment of bladder lesions; however, awareness of potential pitfalls, such as intravesical air secondary to instrumentation, is essential to avoid misdiagnosis.

Ethical considerations

The investigator ensured that the patient fully understood the purpose of this case report, the procedures involved, and the potential risks and benefits.

Declaration of generative AI and AI-assisted technologies in the writing process

During the preparation of this work, the authors used OpenAI’s ChatGPT in order to improve language and readability. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Patient consent

Written informed consent was obtained from the patient for publication. Patient identity and personal data have been protected throughout the manuscript.