Urinary bladder metastasis from suspected second primary breast cancer presenting with ambiguous lower urinary tract symptoms: a case report and literature review

Abstract Background: Secondary urinary bladder tumors arising from solid tumors are rare, and most are direct extensions from other pelvic neoplasms. Bladder metastasis from distant organs is extremely rare. Here, we present a case of breast cancer (BC) that metastasized to the urinary bladder 21 years after the diagnosis of primary BC. Case presentation: A 67-year-old female patient underwent modified radical mastectomy of the right breast for stage I (T1N0M0)papillary carcinoma, which was positive for estrogen and progesterone receptors. Twenty-one years later, she visited the outpatient urology clinic with urinary frequency, urgency, and incontinence; fullness in the lower abdomen; and nocturia. Several medical treatments were administered, but symptoms persisted and even worsened. Urinary bladder ultrasound and abdominal computer tomography revealed diffuse bladder wall thickening with a tumor in the right posterior wall. Tumor markers, including alpha-fetoprotein, carcinoembryonic antigen, carbohydrate antigen 125, and carbohydrate antigen 199, were elevated but carbohydrate antigen 15-3 was within the normal range.The patient underwent cystofibroscopy, and random biopsy specimens were collected. Inflammatory changes in the urinary bladder observed during cystofibroscopy were compatible with bladder wall thickening. The pathologic examination revealed metastatic infiltrating lobular carcinoma with triple-negative molecular subtype, which was different than the type of BC diagnosed 21 years ago. We were unable to confirm whether the origin was a second primary BC or the initial BC owing to the limitations related to available immunostaining markers and pathologic sectioning 21 years earlier. Conclusion: The present case illustrates the critical importance of history-taking in the definitive diagnosis of metastatic cancers in the bladder. Common urinary symptoms may arise from metastasis from uncommon sites. In patients with a history of cancer, the focus should not only be on the currently affected organ but also on the status of the underlying malignancy.