Cryptogenic Organizing Pneumonia: Mystery Behind an Idiopathic Lung Disorder

Introduction:

Cryptogenic organizing pneumonia is a form of interstitial lung disease characterized by the inflammation and scarring of the lungs followed by the obstruction of small airways and the air sacs of the lungs. The term “organized pneumonia” refers to the arrangement of organized swirls of inflammatory tissue filling the spaces of bronchioles and the alveoli (air sacs).

What Are the Causes of Cryptogenic Organizing Pneumonia?

The term “cryptogenic” is mentioned because, in most cases, the cause is unknown. But there are many possible causes, and these include:

• Exposure to certain chemicals.

• Radiation therapy.

• Exposure to birds.

• Post-respiratory infections as a side-effect of organ transplantation.

• Side effects of certain medications.

• Lung abscess.

• Lymphoma.

• Lung cancer.

What Are the Symptoms of Cryptogenic Organizing Pneumonia?

The symptoms of cryptogenic organizing pneumonia are most commonly similar to those of flu symptoms, and these include:

• Shortness of breath (on exertion).

• Dry cough.

• Weight loss.

• Chest pain.

• Joint pain.

• Hemoptysis (coughing up blood).

• Night sweats.

The most common symptoms include-

• Persistent nonproductive cough (up to two to four months).

• Chills and shaking.

• Fatigue.

• Fever.

• Shortness of breath.

• Loss of appetite.

• Weight loss.

Who Is at Risk of Cryptogenic Organizing Pneumonia?

• Both men and women are equally affected. It can be seen most commonly in middle-aged people around fifty to sixty years.

• People with infectious diseases such as rheumatoid arthritis, scleroderma, and lupus erythematosus are at higher risk of developing this condition.

• People with long-term medications are susceptible to this condition.

How Are Cryptogenic Organizing Pneumonia Diagnosed?

Cryptogenic organizing pneumonia requires primarily imaging tests, and to attain a clear diagnosis, in some cases, surgical lung biopsy is carried out. On physical examination, the most common findings are inspiratory crackles.

• High-Resolution Computed Tomography (HRCT): This test reveals patchy air space consolidation, which is most commonly present in 90 % of patients, small nodular opacities, ground-glass opacities, and bronchial wall thickening and dilation. This test can provide more defined details showing more extensive diseases than expected from chest X-ray reviews. The lower lung zone and the lungs' periphery both have a higher prevalence of patchy opacities.

• Chest X-ray: The chest X-ray demonstrates diffuse, bilateral, peripherally distributed alveolar opacities with normal lung volumes. Occasionally, these peripheral opacities are unilateral. Interstitial opacities with honeycombing or irregular linear or nodular opacities are uncommon. Pulmonary opacities that are recurrent or migratory are frequently visible.

• Pulmonary Function Tests: The results of pulmonary function tests are occasionally normal; usually, they show a restrictive defect. However, 21 percent of patients have an obstructive defect in which the ratio of forced expiratory volume in a second to forced vital capacity is less than 70 percent.

• Routine Laboratory Tests: These test results are considered to be nonspecific. The initial value of the erythrocyte sedimentation rate is elevated. However, the leukocytosis test reveals that approximately half of the patients experience increased eosinophils.

• Lung Biopsy: It is performed either bronchoscopic or surgically. It is carried out in cases of excessive proliferation of granulation tissue within bronchioles and alveoli (air sacs). The sample of organizing pneumonia is nonspecific as they occur secondary to other pathological infections such as lymphoma, vasculitis, other interstitial lung diseases such as connective tissue-related interstitial lung disease, idiopathic pulmonary fibrosis, hypersensitivity pneumonitis, and chronic eosinophilic pneumonia.

What Are the Treatment Approaches in Cryptogenic Organizing Pneumonia?

• People with milder forms of cryptogenic organizing pneumonia recover on their own.

• In most cases, some forms of treatment are required.

Drug Therapy:

• Corticosteroids, such as Prednisone, are commonly prescribed medication for a few weeks to a few months.

• It is more important to follow the medication as prescribed.

• If improvement is not seen even after a few weeks, cytotoxic medications such as Cyclophosphamide can be used.

• This condition responds less to antibiotics; hence, the administration of antibiotics is not recommended.

• It is more important for the patients to keep in touch with follow-ups and monitor their progress because of the higher chances of recurrence.

Glucocorticoid Therapy:

• The most preferred treatment for symptomatic patients with respiratory complications due to cryptogenic organizing pneumonia is glucocorticoid therapy.

• The initial dose is started with 0.5 to 1 milligram of Prednisone per kilogram of body weight per day, up to a maximum of 60 milligrams per day, given as a single dose in the morning for two to four weeks.

• Later, depending on the clinical response, the dose is tapered to 0.25 milligrams per kilogram per day to complete four to six months of therapy.

• The patient's condition is observed for the next six to twelve months. If the patient’s condition improves or remains stable, the glucocorticoid dosage is gradually tapered to zero.

• For patients with severe complications, high doses of glucocorticoid therapy are recommended. High-dose glucocorticoid therapy with Methylprednisolone - 500 to 1000 milligrams administered intravenously daily for three to five days is required. Once the condition is improved, oral therapy is followed.

• Relapses usually occur when the treatment is reduced or stopped quickly. It occurs when the Prednisone dose is reduced to 15 milligrams per day or less.

• The other factors influencing relapse include-

• Delay in diagnosis.

• Delay in treatment.

• Severity in diseases including multifocal opacities.

• Abnormal diffusing capacity for carbon monoxide.

• Presence of cholestasis.

• Hypoxemia.

• Scarring and remodeling of the lung parenchyma.

• These kinds of relapses are generally treated by increasing or resuming glucocorticoid therapy.

Cytotoxic Therapy:

• This therapy is followed only if there is no progress in other treatments.

• In patients with normal renal function, the initial dose of Azathioprine is given up to one to two milligrams per day once daily. The maximum dosage can be given up to 150 milligrams per day. A dosage of 50 milligrams daily was given initially, and gradually increased the dose over a period of two to four weeks for at least three months.

• Cyclophosphamide therapy should be discontinued after six months.

Mycophenolate Mofetil and Other Agents:

• In glucocorticoid-resistant organizing pneumonia, Mycophenolate mofetil acts as an inhibitor of proliferating lymphocytes and is increasingly used in the treatment of fibrotic lung disease, including cryptogenic organizing pneumonia.

• Reports suggesting that Cyclosporine, Rituximab, and intravenous immunoglobulin should be used along with glucocorticoids have shown limited success in treating rapidly progressive disease or glucocorticoid-resistant organizing pneumonia.

Conclusion:

The response and prognosis of patients with cryptogenic organizing pneumonia are generally excellent. With glucocorticoid therapy, the span of hospitalization is less than three weeks, and the condition has rapidly improved. The death rate in this condition is usually 10 percent and is most often unrelated to cryptogenic organizing pneumonia and is usually reported in secondary organizing pneumonia due to the underlying illness.