<prompt> Diagnostic features of allergic bronchopulmonary aspergillosis ABPA includeChanging pulmonary infiltratesPeripheral eosinophiliaSerum precipitins against aspergillosis fumigantsOccurance in patients with old cavitatory lesions  <response>: ABPA is a distinct diagnosis from simple asthma, characterized by prominent peripheral eosinophilia and elevated circulating levels of IgE 417 IUmL. Establishing a diagnosis of ABPA also requires establishing sensitivity to Aspergillus antigens by skin test reactivity, positive serum precipitins for Aspergillus, andor direct measurement of circulating specific IgG and IgE to Aspergillus. Central bronchiectasis is described as a classic finding on chest imaging in ABPA but is not necessary for making a diagnosis. Other possible findings on chest imaging include patchy infiltrates and evidence of mucus impaction. Ref Harrison 19th edition pg 1686 