The exact criteria for the diagnosis of<unk>  are not yet universally agreed upon, though working groups have proposed specific guidelines. Minimal criteria include five factors: the presence of asthma and/or cystic fibrosis, a positive skin test to Aspergillus sp., total serum IgE > 416 IU/mL (or kU/L), an increased Aspergillus species–specific IgE and IgG antibodies, and the presence of infiltrates on a chest X-ray.<unk>  should be suspected in patients with a predisposing lung disease—most commonly asthma or cystic fibrosis— and is often associated with chronic airway limitation (CAL). Patients generally present with symptoms of recurrent infection such as fever, but do not respond to conventional antibiotic therapy. Poorly-controlled asthma is a common finding, with a case series only finding 19% of<unk>  patients with well-controlled asthma. Wheezing and hemoptysis (coughing up blood) are common features, and mucus plugging is seen in 31–69% of patients. Blood tests and serology The first stage involves exposing the skin to Aspergillus fumigatus antigens; an immediate reaction is hallmark of<unk> . The test should be performed first by skin prick testing, and if negative followed with an intradermal injection. The overall sensitivity of the procedure is around 90%, though up to 40% of asthmatic patients without<unk>  can still show some sensitivity to Aspergillus antigens (a phenomenon likely linked to a less severe form of<unk>  termed severe asthma with fungal sensitization (SAFS)). Serum blood tests are an important marker of disease severity and are also useful for the primary diagnosis of<unk> . When serum IgE is normal (and patients are not being treated by glucocorticoid medications),<unk>  is excluded as the cause of symptoms. A raised IgE increases suspicion, though there is no universally accepted cut-off value. Values can be stated in international units (IU/mL) or ng/mL, where 1 IU is equal to 2.4 ng/mL. Since studies began documenting IgE levels in<unk>  during the 1970s, various cut-offs between 833 and 1000 IU/mL have been employed to both exclude<unk>  and to warrant further serological testing. The current consensus is that a cut-off of 1000 IU/mL should be employed, as lower values are encountered in SAFS and asthmatic sensitization. IgG antibody precipitin testing from serum is useful, as positive results are found in between 69 and 90% of patients, though also in 10% of asthmatics with and without SAFS. Therefore, it must be used in conjunction with other tests. Various forms exist, including enzyme-linked immunosorbent assay (ELISA) and fluorescent enzyme immunoassay (FEIA). Both are more sensitive than conventional counterimmunoelectrophoresis. IgG may not be entirely specific for<unk> , as high levels are also found in chronic pulmonary<unk>  (CPA) alongside more severe radiological findings. Until recently, peripheral eosinophilia (high eosinophil counts) was considered partly indicative of<unk> . More recent studies show that only 40% of<unk>  sufferers present with eosinophilia, and hence a low eosinophil count does not necessarily exclude<unk> ; for example patients undergoing steroid therapy have lower eosinophil counts. Radiological investigation Consolidation and mucoid impaction are the most commonly described radiological features described in<unk>  literature, though much of the evidence for consolidation comes from before the development of computed tomography (CT) scans. Tramline shadowing, finger-in-glove opacities and ‘toothpaste shadows’ are also prevalent findings. When utilising high-resolution CT scans, there can be a better assessment of the distribution and pattern of bronchiectasis within the lungs, and hence this is the tool of choice in the radiological diagnosis of<unk> . Central (confined to medial two-thirds of the medial half of the lung) bronchiectasis that peripherally tapers bronchi is considered a requirement for<unk>  pathophysiology, though in up to 43% of cases there is a considerable extension to the periphery of the lung. Mucoid impaction of the upper and lower airways is a common finding. Plugs are hypodense but appear on CT with high attenuation (over 70 Hounsfield units) in up to 20% of patients. Where present it is a strong diagnostic factor of<unk>  and distinguishes symptoms from other causes of bronchiectasis. CT scans may more rarely reveal mosaic-appearance attenuation, centrilobular lung nodules, tree-in-bud opacities and pleuropulmonary fibrosis (a finding consistent with CPA, a disease with<unk>  as a known precursor). Rarely other manifestations can be seen on CT scans, including military nodular opacities, perihilar opacities (that mimic hilar lymphadenopathy), pleural effusions and pulmonary masses. Cavitation and aspergilloma are rarer findings, not exceeding 20% of patients, and likely represent a shift from<unk>  to CPA if accompanied by pleural thickening or fibrocavitary disease. Culture Culturing fungi from sputum is a supportive test in the diagnosis of<unk> , but is not 100% specific for<unk>  as A. fumigatus is ubiquitous and commonly isolated from lung expectorant in other diseases. Nevertheless, between 40 and 60% of patients do have positive cultures depending on the number of samples taken. Staging New criteria by the<unk>  Complicated Asthma ISHAM Working Group suggests a 6-stage criteria for the diagnosis of<unk> , though this is yet to be formalised into official guidelines. This would replace the current gold standard staging protocol devised by Patterson and colleagues. Stage 0 would represent an asymptomatic form of<unk> , with controlled asthma but still fulfilling the fundamental diagnostic requirements of a positive skin test with elevated total IgE (>1000 IU/mL). Stage 6 is an advanced<unk> , with the presence of type II respiratory failure or pulmonary heart disease, with radiological evidence of severe fibrosis consistent with<unk>  on a high-resolution CT scan. It must be diagnosed after excluding the other, reversible causes of acute respiratory failure.
Allergic bronchopulmonary aspergillosis
Chronic pulmonary aspergillosis
Tuberculosis
Miliary tuberculosis
Fungal pneumonia
Primary pulmonary coccidioidomycosis
Cryptogenic organizing pneumonia
Atypical pneumonia