Bladder Metastases from Breast Cancer: Managing the Unexpected. A Systematic Review.

Breast cancer (BrC) has the highest incidence among females world over and it is one of the most common causes of death from cancer overall. Its high mortality is mostly due to its propensity to rapidly spread to other organs through lymphatic and blood vessels in spite of proper treatment. Bladder metastases from BrC are rare, with 50 cases having been reported in the last 60 years. This review aims to discuss some critical points regarding this uncommon condition. First, we performed a systematic review of the literature in order to draw a clinical and pathological profile of this entity. On this basis, its features in terms of diagnostic issues, imaging techniques, and survival are critically examined. Most bladder metastases from BrC are secondary lobular carcinoma, which mimic very closely the rare variant of urothelial cancer with lobular carcinoma-like features (uniform cells with an uncohesive single-cell, diffusely invasive growth pattern); thus, immunohistochemistry is mandatory to arrive at a correct diagnosis. This article summarizes the current knowledge regarding the incidence, clinical presentation, diagnosis, prognosis, and treatment of bladder metastases in patients with BrC.