Peripheral eosinophilia with hypoxia

53 yo F smoker, presenting with acute onset hypoxia and found to have a 33% peripheral eosinophilia (abs eos 1.8). CXR had some increased interstitial markings and LLL ?atelectatic plates/vague infiltrate. CTPA was neg for PE but did show groud glass opacity alongwith tree in bud appearance in LUL. She was empirically started on PO steroids for presumed acute eosinophilic pneumonia and also for HAP simultaneously.

Broad ddx included consideration of acute eosinophilic PNAs, visceral larva migrans/ Loeffler’s syndrome, DRESS, paraneoplastic syndrome, allergic broncho-pulmonary aspergillosis, medication induced

– Acute eosinophilic PNA is a diagnosis of exclusion with onset of symptoms <7 days

– In AEP steroids promptly improve symptoms within 12-24 hours

– AEP diagnosis can be made in the appropriate clinical setting, based on CT/CXR, peripheral eosinophilia after exclusion of other causes of eosinophilia, response to steroids and a BAL may not always be needed. BAL should be considered however, if there is any suspicion of Churg Strauss sydrome (as this involves multiple organs) and for steroid-refractory disease for consideration of other second line options.

– Most suggestive CT findings for AEP (in the appropriate clinical setting) a triad of interlobular septal thickening, broncho vascular bundle thickening and pleural effusion. In addition commonly ground glass opacity is also seen.