How do you proceed if a breast cancer patient has imaging concerning for pulmonary lymphangitic carcinomatosis but no other evidence of metastatic disease?  

The first step is to obtain pathologic confirmation, and exclude other causes of imaging findings. This is challenging, but bronchoscopy with BAL washing and possible biopsy would be the best way to go. If diagnosis is confirmed, the treatment would be based on biologic subtype of breast cancer (for...