Urinary bladder metastasis (UBM) from breast cancer is extremely rare and often overlooked. Invasive lobular carcinoma (ILC) has a higher tendency than ductal carcinoma to metastasize to gastrointestinal and genitourinary tracts.

(Case Presentation) We report a case of a 60-year-old woman with a history of stage IIIC breast cancer, diabetes mellitus, and stage 4 chronic kidney disease. She presented with persistent gross hematuria for months. Initial evaluation revealed bilateral hydronephrosis, acute kidney injury, and urinary tract infection. CT imaging showed bladder wall diffused thickening. Bilateral percutaneous nephrostomy (PCN) was performed. Despite the intervention, the patient developed septic shock and was transferred to ICU. A subsequent CT scan revealed pneumoperitoneum, prompting emergency laparotomy, which revealed transverse colon perforation with pelvic organ adhesion. Cystoscopy showed multiple papillary and sessile bladder masses. TURBT was performed. Pathology revealed poorly differentiated carcinoma. Immunohistochemistry (IHC) profile showed AE1/AE3(+), GATA3(+), mammaglobin(+), ER(-), PR(-), and P63(-), suggesting a secondary carcinoma of breast origin. Unfortunately, the patient passed away due to severe septic shock and multiple organ failure related to intra-abdominal infection.

(Discussion) UBM from breast cancer is a rare but important differential diagnosis, especially in patients with a history of breast cancer presenting with hematuria. Invasive lobular carcinoma is more prone to metastasize to mucosal surfaces and can present as diffuse bladder wall thickening rather than distinct masses. Diagnosis relies heavily on cystoscopy and histopathology, especially IHC staining to differentiate primary from metastatic origin. This case also highlights the atypical presentation and challenges in management. Most UBMs occur in the setting of widespread disease and have a poor prognosis, with average survival ranging from 18 to 30 months. However, the prognosis worsens when the diagnosis is delayed or complicated by systemic infection, as in this case.

Urinary bladder metastasis from breast cancer is rare and often presents as painless gross hematuria. It should be considered in the differential diagnosis in patients with a breast cancer history, regardless of the time since initial diagnosis. Cystoscopy and tissue biopsy remain essential for diagnosis. Due to its association with advanced disease and poor prognosis, early recognition and appropriate systemic therapy are critical.