Bronchiolitis obliterans with organizing pneumonia
BRONCHIOLITIS OBLITERANS WITH ORGANIZING PNEUMONIA (BOOP)
BRONCHIOLITIS OBLITERANS WITH ORGANIZING PNEUMONIA (BOOP) DEFINITION
Previously called bronchiolitis obliterans with organizing pneumonia, cryptogenic organizing pneumonia (COP) is a rare lung condition in which the small airways (bronchioles), the tiny air-exchange sacs (alveoli) and the walls of small bronchi become inflamed and plugged with connective tissue. The condition is called “cryptogenic” because the cause is unknown.
Most people who have COP experience a persistent nonproductive cough and — depending on how much of the lung is affected — shortness of breath with exertion.
Before diagnosing COP, your doctor will want to rule out other possible causes of pneumonia, such as:
- Bacterial, viral or fungal infections
- Expose to drugs such as cocaine, gold salts, and some antibiotics and anti-seizure medications
- Inflammatory disorders such as lupus, rheumatoid arthritis or scleroderma
- Bone marrow, lung, kidney and stem cell transplants
- Certain types of chemotherapy or radiation to the chest
Most people with COP recover after weeks or months of treatment with steroids. In some cases, however, COP can progress despite treatment.
BRONCHIOLITIS OBLITERANS WITH ORGANIZING PNEUMONIA (BOOP) CAUSES
In most cases, the cause of BOOP is unknown and is referred to as idiopathic BOOP. Causes of BOOP include radiation therapy; exposure to certain fumes or chemicals, post respiratory infections, after organ transplantation; and from more than 35 medications. Systemic disorders associated with BOOP include the connective-tissue diseases, immunological disorders, and inflammatory bowel disease. BOOP has also been seen in association with lung abscess, lung cancer, and lymphoma. Importantly, the BOOP lesion is seen in individuals with idiopathic pulmonary fibrosis, or IPF, and in these situations, the primary lung disease is the IPF and the secondary process is BOOP.
BRONCHIOLITIS OBLITERANS WITH ORGANIZING PNEUMONIA (BOOP) PATHOPHYSIOLOGY
Bronchiolitis obliterans organizing pneumonia (BOOP) was first described in the early 1980s as a clinicopathologic syndrome characterized symptomatically by subacute or chronic respiratory illness and histopathologically by the presence of granulation tissue in the bronchiolar lumen, alveolar ducts and some alveoli, associated with a variable degree of interstitial and airspace infiltration by mononuclear cells and foamy macrophages. Persons of all ages can be affected. Dry cough and shortness of breath of 2 weeks to 2 months in duration usually characterizes BOOP. Symptoms persist despite antibiotic therapy. On imaging, air space consolidation can be indistinguishable from chronic eosinophilic pneumonia (CEP), interstitial pneumonitis (acute, nonspecific and usual interstitial pneumonitis, neoplasm, inflammation and infection). The definitive diagnosis is achieved by tissue biopsy. Patients with BOOP respond favorably to treatment with steroids.
BRONCHIOLITIS OBLITERANS WITH ORGANIZING PNEUMONIA (BOOP) SYMPTOMS
Symptoms of BOOP vary from case-to-case depending upon the specific type. For example, people with idiopathic BOOP have a flu-like illness, while people with BOOP associated with an underlying connective-tissue disorder have cough or shortness of breath. Some individuals with BOOP such as focal BOOP may have no apparent symptoms, while others may have severe respiratory distress as in acute, rapidly-progressive BOOP.
Symptoms usually develop slowly over a few weeks or months. The most common symptom is a persistent, nonproductive cough. Some affected individuals develop a flu-like illness characterized by a sore throat, a general feeling of ill health (malaise), weight loss, and fatigue. Eventually, shortness of breath especially from exertional activities may develop. The shortness of breath and cough may become progressively worse.
Individuals with BOOP may develop small crackling or rattling sounds in the lung (crackles or rales) that are apparent upon physical examination. In rare cases affected individuals may experience chest pain, joint pain (arthralgia), night sweats or coughing up blood (hemoptysis).
A rapidly progressive form of BOOP exists that can progress from symptom onset to acute respiratory failure in only a few days. This form of BOOP may be associated with an underlying fibrotic process.
BRONCHIOLITIS OBLITERANS WITH ORGANIZING PNEUMONIA (BOOP) DIAGNOSIS
Bronchiolitis obliterans organizing pneumonia (BOOP) is a rare inflammatory lung disorder. Symptoms of BOOP include a flu-like illness in many individuals, cough and shortness of breath with exertional activities. Wheezing and hemoptysis are rare. The term bronchiolitis obliterans refers to swirls or plugs of fibrous, granulation tissue filling the small bronchiole airways. Organizing pneumonia refers to organized swirls of inflammatory tissue filling the small spherical units of the lungs referred to as alveoli and the alveolar ducts. Individuals with BOOP experience inflammation of the bronchioles and alveolar lung spherical units simultaneously, which distinguishes it from other similar inflammatory lung disorders.
Although several different known causes of BOOP have been identified, most cases occur for no known reason (idiopathic). Idiopathic BOOP may also be called cryptogenic organizing pneumonia. Some researchers prefer the use of COP to avoid confusion with other lung disorders with similar names. The term cryptogenic denotes that the cause of the disorder is unknown. Others prefer the term BOOP because it the most recognized term for the disorder, and others refer to it as Epler’s pneumonia.
BRONCHIOLITIS OBLITERANS WITH ORGANIZING PNEUMONIA (BOOP) TREATMENT
In some cases, the symptoms of BOOP may resolve without treatment especially the post breast radiation-type. In some mild cases such as individuals without symptoms or who have non-progressive disease, the process can be monitored and treated later if necessary. Most individuals with BOOP require treatment with the anti-inflammatory, corticosteroid medication, usually in the form of prednisone. This therapy often results in dramatic improvement with resolution of symptoms within days or weeks. In some situations, the BOOP may recur as the dose is decreased, but the BOOP will respond to an additional course of treatment.
The rapidly progressive form of BOOP is treated with intravenous corticosteroid medication and sometimes with Cytoxan. Individuals wit. secondary BOOP may improve after treating the underlying condition. Additional treatment is symptomatic and supportive.