Bronchiolitis obliterans organizing pneumonia
Overview
Bronchiolitis obliterans organizing pneumonia (BOOP) is an inflammation of the bronchioles (bronchiolitis)and surrounding tissue in the lungs. BOOP is often caused by a pre-existing chronic inflammatory disease like rheumatoid arthritis. BOOP can also be a side effect of certain medicinal drugs, e.g. amiodarone. It is also known as cryptogenic organizing pneumonia (COP), though some sources recommend using the latter term, to reduce confusion with bronchiolitis obliterans.[
Symptoms
* Cough * Dyspnea * Influenza-like symptoms * febrile illness * widespread crackles * mild resting hypoxemia
Diagnosis
On clinical examination, crackles are common, but clubbing is not. Laboratory findings are nonspecific. Almost 75% of people have symptoms for less than two months before seeking medical attention. A flu-like illness, with a cough, fever, a feeling of illness (malaise), fatigue, and weight loss heralds the onset in about 40% of patients. Doctors do not find any specific abnormalities on routine laboratory tests or on a physical examination, except for the frequent presence of crackling sounds (called rales) when the doctor listens with a stethoscope. Pulmonary function tests usually show that the amount of air the lungs can hold is below normal. The amount of oxygen in the blood is often low at rest and is even lower with exercise. The chest x-ray is distinctive with features that appear similar to an extensive pneumonia, with both lungs showing widespread white patches. The white patches may seem to migrate from one area of the lung to another as the disease persists or progresses. Computed Tomography (CT) may be used to confirm the diagnosis. Often the findings are typical enough to allow the doctor to make a diagnosis without ordering additional tests. To confirm the diagnosis, a doctor may perform a lung biopsy using a bronchoscope. Many times, a larger specimen is needed and must be removed surgically.
Treatment
Most patients recover with corticosteroid therapy.[5] A standardized approach to dosing starting at 0.75 mg/kg and weaning over 24 weeks has been shown to reduce total corticosteroid exposure without affecting outcome. About two thirds of patients recover with corticosteroid therapy: the usual steroid administered is Prednisolone in Europe and Prednisone in the USA; these differ by only one functional group and have the same clinical effect. The steroid is initially administered in high dosage, typically 50mg per day tapering down to zero over a 6 month to one year period. If the steroid treatment is halted too quickly the disease may return. Other drugs must be taken to counteract side effects of the steroid.