Primary Urinary Bladder Adenocarcinoma with Signet-Ring Cell Differentiation During Pregnancy Managed by Combined Cesarean Delivery and Radical Cystectomy: A Report of a Rare Case.

Primary urinary bladder adenocarcinoma with signet-ring cell differentiation is an extremely rare and aggressive malignancy. Diagnosis during pregnancy is particularly challenging, as hematuria, anemia, abdominal pain, and pelvic symptoms are often attributed to more common obstetric or gynecologic conditions. The coexistence of pregnancy, obstructive uropathy, and rare bladder histology creates significant diagnostic and therapeutic complexity. We report a rare case of primary urinary bladder adenocarcinoma with mixed mucinous, intestinal, and signet-ring cell differentiation in a 36-year-old pregnant woman. She initially presented with severe anemia and pelvic bleeding, with early imaging suggesting a possible gynecologic mass. She was later lost to follow-up and re-presented at 24 weeks' gestation with gross hematuria, renal impairment, and bilateral obstructive uropathy. MRI demonstrated a large circumferential bladder mass with bilateral hydroureteronephrosis and possible extravesical extension. Bilateral nephrostomy tubes were placed, followed by cystoscopy and transurethral biopsy, confirming primary bladder adenocarcinoma with signet-ring differentiation. After multidisciplinary discussion, she underwent cesarean delivery followed by radical cystectomy, anterior pelvic exenteration, and ileal conduit urinary diversion. Final pathology confirmed poorly differentiated signet-ring cell adenocarcinoma with deep perivesical invasion and negative margins. She later developed metastatic recurrence requiring palliative systemic therapy and radiotherapy. This case highlights the diagnostic difficulty of rare bladder malignancies in pregnancy, which may mimic gynecologic disease and present late with obstructive uropathy and severe anemia. Multidisciplinary management and timely surgical intervention are essential; however, signet-ring-predominant bladder adenocarcinoma may follow an aggressive clinical course despite definitive treatment.