Organizing pneumonia is also known as bronchiolitis obliterans organizing pneumonia (BOOP), and it has two varieties depending on its cause: cryptogenic organizing pneumonia (COP), and secondary organizing pneumonia (SOP). Cryptogenic organizing pneumonia is a pneumonia for which the precipitating cause of illness is unknown, while secondary organizing pneumonia is caused by a specific outside inciting event, such as infection. Bronchiolitis obliterans organizing pneumonia is an inflammation of the airways in which the bronchioles and alveoli that line the lungs are filled with fluid because of an infection. All kinds of pneumonia are caused by bacterial, viral, fungal, or parasitic infection, or they may be triggered by toxic fumes or contact with medical equipment, including respirators.
Organizing pneumonia is characterized by the way in which the lungs and airways recover from the influenza-like infection. In other types of pneumonia, dead cells accumulate into blobs of mucus and dead tissue, which are then coughed out or reabsorbed by the body. With organizing pneumonia, the mucus that is exuded "organizes," or is infiltrated by fibrous tissue from the airways, which is loosened by coughing. This infiltration of tissue and its movement through the lungs causes cicatrization, or scarring, of the lung tissue, which can permanently affect breathing. For this reason, organizing pneumonia is also known as "unresolved pneumonia."
There are many different causes of pneumonia and types of pneumonia disease, but they all refer to an inflammatory condition in the lungs. BOOP is a type of pneumonia that may be caused by infectious or noninfectious agents; it shares this classification with aspiration pneumonia, lipid pneumonia, and eosinophilic pneumonia. Most of the more common varieties of pneumonia are caused by infectious agents. The many different ways of acquiring pneumonia make it difficult to detect the cause of the illness. COP is as common as secondary organizing pneumonia, and treatment for both types of organizing pneumonia is often the same.
As with all pneumonia, organizing pneumonia affects the alveoli, microscopic sacs of air that help the body exchange air through the lungs and airways. If they become clogged because of infection, they become inflamed and can no longer move air effectively. This can lead to symptoms of pneumonia, which include cough or productive cough with mucus, chest pain, fever or chills, fatigue, aches, and trouble breathing. Pneumonia can be fatal and should be treated by a medical professional, who will prescribe rest and a course of antibiotics or steroids to address the underlying infection.