Metastatic ductal adenocarcinoma of the breast presenting with pericardial effusion—Challenges in the diagnosis of breast cancer

Breast cancer is a common entity that can be difficult to diagnose. This case demonstrates the limitations of breast cancer diagnostics. Particularly, how the available imaging techniques and even biopsy can potentially miss a malignancy. It exemplifies the role immunohistochemistry staining plays in the diagnosis of cancers of unclear origin.