56 year old woman with eosinophilia

56-year-old woman with a past medical history of asthma since age 38 with 2 previous courses of steroids, otherwise well controlled who presented with increase in non-productive cough and really very minimal SOB except on exertion. A cxr revealed b/l upper lobe infiltrates. She denies any hemoptysis and has lost about 14 pounds. She initially began her evaluation for this disease process in May 06 by ID. Her appetite is poor.




A CBC showed a white count of 17 with 42% eosinophils.
A BAL showed a cell count of 696 with 20% eosinophils, 40% macrophages, 11% lymphocytes.
A TBBX showed: Active lung injury with eosinophilia. 2. Grocott stain is negative for fungus
Based on this, the pathologist thought the ddx (which is close to mine before I saw the bx results): Diagnostic considerations include acute eosinophilic pneumonia, which is favored, an underlying infectious etiology, and Churg-Strauss syndrome/
Wegener's granulomatosis. Microbiologic and serologic studies would allow for
exclusion of the latter choices.
I would also add ABPA to that list.
Of note, the BAL was negative for all micro.

Now, my question is, would you treat this patient with steroids, since nearly everyhting on that list is trreatable with steroids, or would you proceed to open lung for a definitive dx? The reason for the latter is that even though these disease are all similarly treated, their prognosis and natural courses are different and this would be helpful for future care.
What are your thoughts?