Bladder cancer predominantly manifests as urothelial carcinoma, with signet ring cell carcinoma being an unusually rare variant subtype. Previous studies have indicated that this variant subtype exhibits aggressive behavior and a dismal prognosis. Our report aims to contribute to a rare case in our practice.

A 66-year-old male with no systemic disease presented with gross hematuria and sought medical attention for further evaluation.The serum prostate-specific antigen (PSA) level was 2.76 ng/ml. Abdominal sonography showed that the prostate measured 4.1 × 3.9 × 4.0 cm, with a focal protrusion at the base of the urinary bladder. Urine cytology tested positive for malignant cells. Subsequent abdominal CT imaging suggested a urinary bladder tumor with metastatic lymphadenopathy. As a result, surgical intervention was planned, and the patient underwent a transurethral resection of the bladder tumor (TURBT). Intraoperatively, a non-papillary tumor was observed in the trigone of the urinary bladder, extending to the bladder neck and prostate. Pathological examination confirmed signet-ring cell adenocarcinoma with muscle invasion. For staging purposes, chest CT revealed suspected thrombus formation in the left brachiocephalic vein, left internal jugular vein, and left subclavian vein, as well as borderline-sized lymph nodes in the left lower neck. Upper gastrointestinal (GI) endoscopy and colonoscopy were performed to rule out a GI tract origin but showed no significant findings. The clinical stage was determined to be T4N3M0-1. The oncology team was consulted, and the patient was started on chemotherapy with the FOLFOX regimen (Folinic acid, Fluorouracil, Oxaliplatin). To date, the patient has completed 10 cycles of FOLFOX, with notable improvement in lymphadenopathy and marked regression in venous emboli.

This case highlights the clinical presentation and treatment of signet-ring cell adenocarcinoma of urinary bladder, including gross hematuria which is often found in urothelial carcinoma of urinary bladder. The case also underscores the role of different chemotherapy regimens in treatment. Previous studies have shown that the prognosis of signet-ring cell adenocarcinoma of the urinary bladder is generally poor, with outcomes influenced by factors such as T stage, M stage, lymph node involvement, and the surgical approach.

This emphasizes the critical importance of accurate diagnosis and comprehensive evaluation to guide appropriate treatment strategies and improve patient outcomes.