Intra-diverticular bladder cancer (IDBC) is a rare entity, comprising approximately 1% of all bladder cancers. Its unique anatomical feature—the absence of the muscularis propria—predisposes tumors to early invasion and advanced clinical staging. While most studies emphasize poor prognosis and aggressive treatment, evidence on early-stage IDBC remains limited. This study highlights two early-stage IDBC cases managed with repeated TURBT and intravesical or systemic chemotherapy, with favorable long-term outcomes, underscoring the potential role of conservative strategies in select patients.

We retrospectively collected data on all patients diagnosed with intra-diverticular bladder cancer at Kaohsiung Chang Gung Memorial Hospital between 2017 and 2025. Data collected included baseline characteristics, intraoperative and postoperative outcomes, and a minimum follow-up period of five years. Patients with pathological reports indicating Ta or T1 disease who underwent repeated transurethral resection of bladder tumor, intravesical chemotherapy, or systemic chemotherapy were included. Patients who underwent radical cystectomy or partial cystectomy were excluded from this study.

Two cases of early-stage intra-diverticular bladder cancer (IDBC) were managed with bladder-sparing approaches and followed up for five years. The first case was a 65-year-old male presenting with lower urinary tract symptoms and bilateral hydronephrosis. Imaging and cystoscopy revealed a large (15 × 11 cm) right posterior wall bladder diverticulum containing a papillary tumor. TURBT confirmed high-grade papillary urothelial carcinoma (T1N0). Tumor recurrence was observed during follow-up, requiring a second TURBT. The patient subsequently received intravesical mitomycin C, followed by systemic chemotherapy with gemcitabine, cisplatin, and nivolumab. No tumor recurrence was detected during the five-year period. The second case involved an 82-year-old male with painless hematuria. Cystoscopy and CT revealed a 1.69 cm tumor in a left lateral bladder diverticulum without distant metastasis. TURBT pathology confirmed low-grade papillary urothelial carcinoma (TaN0). The patient received intravesical mitomycin C instillation. During follow-up, small recurrent tumors were managed with laser vaporization, and pathology consistently revealed low-grade disease. No recurrence was detected after five years of surveillance. These cases demonstrate that bladder-sparing strategies, including repeated TURBT, intravesical therapy, and systemic chemotherapy, may be effective in selected patients with early-stage IDBC. Given the absence of muscularis propria in diverticular walls, careful surgical technique is essential to minimize the risk of bladder perforation.

Intra-diverticular bladder cancer is an uncommon condition with an incidence of approximately 1%. The cases presented in our study suggest that conservative management may be a viable treatment option for selected patients in early-stage IDBC.