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Cryptogenic organizing pneumonia
Last reviewed: 12.07.2025
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Cryptogenic organizing pneumonia (bronchiolitis obliterans with organizing pneumonia) is an idiopathic lung disease in which granulation tissue obstructs the bronchioles and alveolar ducts, causing chronic inflammation and organizing pneumonia in adjacent alveoli.
Idiopathic obliterative bronchiolitis with organizing pneumonia (cryptogenic organizing pneumonia) affects men and women, usually between the ages of 40 and 50, with equal frequency. Smoking does not appear to be a risk factor.
[ Symptoms of cryptogenic organizing pneumonia
About half of patients present with symptoms similar to those of community-acquired pneumonia (including persistent influenza-like symptoms characterized by cough, fever, malaise, fatigue, and weight loss). Progressive cough and exertional dyspnea usually prompt the patient to seek medical attention. Physical examination reveals inspiratory wheezing.
Diagnosis of cryptogenic organizing pneumonia
The diagnosis is established by analyzing the anamnestic data, the results of the physical examination, radiographic studies, pulmonary function tests, and histologic examination of biopsy material. Chest radiographic changes are characterized by bilateral diffuse, peripherally localized alveolar opacities with normal lung volumes; peripheral opacities similar to those characteristic of chronic eosinophilic pneumonia may also be present. Rarely, alveolar opacities are unilateral. Recurrent and migratory infiltrates are often observed. Rarely, irregular linear or focal interstitial infiltrates or "honeycombing" may be observed early in the disease. HRCT reveals focal consolidation of air spaces, ground-glass opacities, small nodular opacities, thickening of the walls and dilation of the bronchi. Focal opacities are more common in the peripheral parts of the lower lobes of the lungs. CT may reveal a much larger area of damage than expected from chest X-ray results.
Pulmonary function tests usually reveal restrictive abnormalities, although obstructive abnormalities ([FEV/FVC] < 70%) are seen in 21% of patients; in some cases, lung function is normal.
The test results are nonspecific. Leukocytosis without an increase in the eosinophil count occurs in approximately half of the patients. Initially, the ESR is often elevated. Hypoxemia at rest and under load is usually observed.
Histologic examination of lung tissue biopsy specimens reveals marked proliferation of granulation tissue in the small airways and alveolar ducts with chronic inflammation in the surrounding alveoli. Foci of organizing pneumonia (i.e., changes characteristic of cryptogenic organizing pneumonia) are not specific and may be observed in other pathological processes, including infections, Wegener's granulomatosis, lymphomas, hypersensitivity pneumonitis, and eosinophilic pneumonia.
Treatment of cryptogenic organizing pneumonia
Treatment of cryptogenic organizing pneumonia is similar to that for idiopathic pulmonary fibrosis. Clinical recovery occurs in two-thirds of treated patients, often within 2 weeks.
What is the prognosis for cryptogenic organizing pneumonia?
Cryptogenic organizing pneumonia has a poor prognosis. Relapses occur in 50% of patients, but additional courses of glucocorticoids are characteristic.