Charts were reviewed for demographics, laboratory and imaging findings, and clinical course. 195 patients with suspected “eosinophilic pneumonia” demonstrated pulmonary eosinophilia (as defined above). Of these 195, 12 patients were included and 183 were excluded for various reasons (see Fig. 1). Thirteen patients were excluded due to relapse of symptoms on steroid

taper and 2 patients were click here excluded due to lack of diffuse infiltrates on chest imaging. Five patients had all characteristics consistent with the diagnosis of idiopathic AEP. Three patients were categorized as “probable” idiopathic AEP due to exceeding expected 30-day symptom duration (37 and 38 days) and/or maximal temperature less than 38 ○C and are included in analysis. Four patients were defined as “possible”

idiopathic AEP given history of polymyalgia rheumatica, eczema or allergic rhinitis and are described but not included in analysis. Clinical features of included patients are summarized in Table 1 and Table 2. While BTK inhibitor idiopathic AEP is by definition an acute illness, the symptom duration has been variably defined as less than 7 [11] or less than 30 days [2] without significant differences in the clinical manifestations. We examined all cases of possible idiopathic AEP of less than 45 days duration and describe two cases with symptoms slightly longer than 30 days as “probable” AEP. Although it can be argued that a longer duration of symptoms may lead to confusion with chronic eosinophilic pneumonia, the average duration of symptoms in chronic eosinophilic pneumonia is significantly longer (19.7 weeks) and the disease characteristics are distinct [13]. Likewise the definition of “febrile illness” varies in the reported literature including temperatures as low as 37.2 °C [6] and [12]. We used subjective fevers or a temperature of 38 °C. We have included one patient Flavopiridol (Alvocidib) without fever who was using anti-pyretic agents. Little attention

has been made to the presence or absence of anti-pyretic agents or cooling device use in prior reported cases. Furthermore, patients with sepsis may have an abnormally low temperature in lieu of fever. It is unknown if this is also true of AEP as such patients have by definition been excluded from AEP criteria. With this in mind clinicians should consider AEP in patients in the absence of fever if other features are compatible. Hypoxemia has been typically described as a PaO2 less than 60 mm Hg or a pulse oximetry saturation of less than 90% on room air [2]. However, one recent case series did not use hypoxia/hypoxemia as an inclusion criteria for potential cases of idiopathic AEP [12]. In reviewing the literature, little attention has been paid to desaturation with activity. Some of our patients did not have hypoxia at rest but had hypoxia with minimal exertion. Desaturation with activity should be considered as a criterion for AEP. In patients without hypoxia but with other classic features AEP should be considered.