<unk>  was first described by the university of Minnesota in 1899, however, in 1900, Dr. Lange, a German physician described precise pathology and possible etiologies in two of his patients and therefore, established<unk>  as a separate pathological entity.<unk>  may be classified according to clinical syndromes and histological abnormalities into 6 subtypes:<unk>  obliterans, respiratory<unk> , follicular<unk> , proliferative<unk> , airway-centered interstitial fibrosis, and diffuse panbronchiolitis. The pathogenesis of<unk>  is to be the result of inflammation and immunological responses that cause cellular injury and damage. Eventually, respiratory compromise results, which may be irreversible and fatal. Associated conditions include asthma and primary immunodeficiencies. The gross pathology of<unk>  includes bronchiolar and airway destruction. Microscopically, fibroblasts and lymphocytes are noted.Common causes of<unk>  include inhalational injury, viral, and drug induced, such as, mineral dusts, diacetyl, RSV and busulfan. The incidence for<unk>  is not well recorded, it is estimated that in the USA 3 per 100,000 of all community acquired pneumonias have underlying<unk> . The prevalence of<unk> -onset<unk>  is unknown. The most common cause of<unk>  in<unk> s is RSV, most<unk> s tend to be asymptomatic or carriers and therefore, prevalence is difficult to stipulate. The attack rate for death caused by<unk>  complicated by pneumonia in elderly homes is approximately 3 per 100,000. The incidence of<unk>  increases with age; the median age at diagnosis is 68 years. There is no racial predilection in<unk> s. Men are more commonly affected by<unk>  than women, and tend to have higher mortality rates. Diffuse panbronchiolitis is a common disease that tends to affect Japan. Those of Hispanic, Native American and Alaskan origins tend to have a higher likelihood of hospitalization. Developed and developing countries tend to have similar incidence, hospitalisation and mortality rates. Risk factors in the development of<unk>  include smoking, cardiovascular disease, respiratory disease, immunodeficiency and immunosuppression. If left untreated, patients with<unk>  may progress to develop cough, wheezing, and dyspnea. Common complications of<unk>  include chronic bronchitis, pneumonia, and death. Prognosis is generally excellent if viral in origin with full recovery upon completion of treatment. However, occupational<unk>  tends to be irreversible and permanent. There is no single diagnostic study of choice for the diagnosis of<unk> , the gold standard for diagnosis of<unk>  is clinical assessment. However, pulmonary function testing, high resolution computed tomography (HRCT), and bronchoscopy may be useful in the diagnosis of<unk> .A positive history of insidious onset of cough, wheezing and dyspnea with deteriorating pulmonary function is suggestive of<unk> . The most common symptoms of<unk>  include cough, wheeze and shortness of breath. Less common symptoms of<unk>  include hemoptysis, dehydration and loss of appetite. Patients with<unk>  usually appear lethargic. Physical examination of patients with<unk>  is usually remarkable for bilateral basilar lung crackles, tachypnea, wheezing and sometimes, a low grade fever.There are no diagnostic laboratory findings associated with<unk> . However, the following laboratory investigations may be helpful in the diagnosis of<unk> , complete blood count, white blood cell count, C-reactive protein, blood culture, rapid viral antigen testing, arterial blood gases, pulse oximetry, urine analysis, sputum analysis, CSF analysis and culture. High resolution chest CT scan may be helpful in the diagnosis of<unk> . Findings on CT scan suggestive of<unk>  include mosaic or diffuse air trapping, bronchial wall thickening, linear opacities, centrilobular nodules, and bronchiectasis (dilated airways). Oxygen-sensitive 3He-MRI in useful in<unk>  obliterans syndrome after lung or heart or kidney transplantation. Normal grafts have a higher oxygen distribution than those grafts with<unk>  obliterans syndrome (BOS). There are no MRI findings associated with<unk> . Other diagnostic studies for<unk>  include lung biopsy, which rules out other causes of dyspnea and can confirm<unk>  obliterans syndrome, and histopathology, which demonstrates abnormalities in the walls of membranous or respiratory bronchioles, tubular narrowing or total obliteration of the lumen, concentric T lymphocyte infiltration, smooth muscle hypertrophy in the small airways, bronchiolectasia with mucus plugging, and fibrosis and scarring. The optimal medical therapy for<unk>  is unknown. Therapy is mainly the cessation of exposure to irritant agent.<unk>  is treated based on severity, however, the disease is progressive and inevitably, leads to respiratory failure. Therefore, supportive therapy includes supplemental oxygen, bronchodilators, cough suppressant, anti-reflux therapy, macrolides, immunosuppressants and glucocorticoids. Bronchodilators and glucocorticoids have been heavily criticized in their role of improving symptoms, and are reserved only in those who show clinical improvement. Lung transplant is not the first-line treatment option for patients with<unk> . Surgery is usually reserved for patients with untreatable and advanced stage lung disease.Effective measures for the primary prevention of<unk>  include the cessation of exposure to inhalants, prevention of smoking, vaping and smoking cessation, health awareness, and routine surveillance. Treating comorbidities and also reducing exposure through the use of medical masks and respirators, robots, isolation of harmful processes, ventilation, limiting exposure hours, maintenance of dust control systems, and the use of warning signs.
Adult bronchiolitis
Croup
Community acquired pneumonia
Community-acquired pneumonia
Acute bronchitis
Severe acute respiratory syndrome
CMV pneumonitis
Viral pneumonia