High resolution computed tomography (HRCT) images of the lower chest in a 16-year-old boy initially diagnosed with<unk>  (left), and 8 weeks later (right) after a 6-week course of treatment with erythromycin. The bilateral bronchiectasis and prominent centri-lobular nodules with a "tree-in-bud" pattern shows noticeable improvement. The diagnosis of<unk>  requires analysis of the lungs and bronchiolar tissues, which can require a lung biopsy, or the more preferred high resolution computed tomography (HRCT) scan of the lungs. The diagnostic criteria include severe inflammation in all layers of the respiratory bronchioles and lung tissue lesions that appear as nodules within the terminal and respiratory bronchioles in both lungs. The nodules in<unk>  appear as opaque lumps when viewed on X-rays of the lung, and can cause airway obstruction, which is evaluated by a pulmonary function test, or PFT. Lung X-rays can also reveal dilation of the bronchiolar passages, another sign of<unk> . HRCT scans often show blockages of some bronchiolar passages with mucus, which is referred to as the "tree-in-bud" pattern. Hypoxemia, another sign of breathing difficulty, is revealed by measuring the oxygen and carbon dioxide content of the blood, using a blood test called arterial blood gas. Other findings observed with<unk>  include the proliferation of lymphocytes (white blood cells that fight infection), neutrophils, and foamy histiocytes (tissue macrophages) in the lung lining. Bacteria such as H. influenzae and P. aeruginosa are also detectable, with the latter becoming more prominent as the disease progresses. The white blood, bacterial and other cellular content of the blood can be measured by taking a complete blood count (CBC). Elevated levels of IgG and IgA (classes of immunoglobulins) may be seen, as well as the presence of rheumatoid factor (an indicator of autoimmunity). Hemagglutination, a clumping of red blood cells in response to the presence of antibodies in the blood, may also occur. Neutrophils, beta-defensins, leukotrienes, and chemokines can also be detected in bronchoalveolar lavage fluid injected then removed from the bronchiolar airways of individuals with<unk> , for evaluation. Differential diagnosis In the differential diagnosis (finding the correct diagnosis between diseases that have overlapping features) of some obstructive lung diseases,<unk>  is often considered. A number of<unk>  symptoms resemble those found with other obstructive lung diseases such as asthma, chronic bronchitis, and emphysema. Wheezing, coughing with sputum production, and shortness of breath are common symptoms in such diseases, and obstructive respiratory functional impairment is found on pulmonary function testing. Cystic fibrosis, like<unk> , causes severe lung inflammation, excess mucus production, and infection; but<unk>  does not cause disturbances of the pancreas nor the electrolytes, as does CF, so the two diseases are different and probably unrelated.<unk>  is distinguished by the presence of lesions that appear on X-rays as nodules in the bronchioles of both lungs; inflammation in all tissue layers of the respiratory bronchioles; and its higher prevalence among individuals with East Asian lineage.<unk>  and bronchiolitis obliterans are two forms of primary bronchiolitis. Specific overlapping features of both diseases include strong cough with large amounts of often pus-filled sputum; nodules viewable on lung X-rays in the lower bronchi and bronchiolar area; and chronic sinusitis. In<unk> , the nodules are more restricted to the respiratory bronchioles, while in OB they are often found in the membranous bronchioles (the initial non-cartilaginous section of the bronchiole, that divides from the tertiary bronchus) up to the secondary bronchus. OB is a bronchiolar disease with worldwide prevalence, while<unk>  has more localized prevalence, predominantly in Japan. Prior to clinical recognition of<unk>  in recent years, it was often misdiagnosed as bronchiectasia, COPD, IPF, phthisis miliaris, sarcoidosis or alveolar cell carcinoma.
Diffuse panbronchiolitis
Emphysema
Acute eosinophilic pneumonia
Plastic bronchitis
Cryptogenic organizing pneumonia
Eosinophilic bronchitis
Hypersensitivity pneumonitis
Mineral dust airway disease