From the Guidelines
Idiopathic interstitial pneumonias, including cryptogenic organizing pneumonia, should be treated with oral corticosteroids as the first-line treatment, with a recommended dose of 0.5-1 mg/kg/day of prednisone for 1-3 months, followed by a slow taper over 3-6 months to prevent relapse, as this approach has been shown to result in clinical recovery in the majority of patients 1. The diagnosis of idiopathic interstitial pneumonias, including cryptogenic organizing pneumonia, is based on a combination of clinical, radiological, and histopathological findings. The disease is characterized by the presence of granulation tissue plugs within small airways, alveolar ducts, and alveoli, and is often associated with a subacute illness of relatively short duration, with variable degrees of cough and dyspnea 1. Some key features of the disease include:
- A subacute illness of relatively short duration, with variable degrees of cough and dyspnea
- Patchy and often migratory consolidation on HRCT, commonly associated with ground-glass opacity
- Perilobular opacities and reversed halo sign may be helpful in suggesting the diagnosis
- Small unilateral or bilateral pleural effusion may occur in 10-30% of patients The majority of patients with cryptogenic organizing pneumonia recover completely with oral corticosteroids, but relapse is common, and some patients may experience residual or progressive interstitial fibrosis despite prolonged treatment 1. Alternative treatments for steroid-resistant cases or those who cannot tolerate steroids include macrolides, mycophenolate mofetil, or cyclophosphamide, and patients should be monitored with pulmonary function tests and imaging during treatment 1. It's worth noting that the pathophysiology of the disease involves an abnormal healing response to lung injury, with excessive proliferation of granulation tissue rather than normal resolution of inflammation, and that the disease has a favorable prognosis with appropriate treatment, though approximately 30% of patients may experience relapse when steroids are tapered or discontinued 1.
From the Research
Definition and Classification
- Idiopathic interstitial pneumonias (IIPs) are a group of diffuse parenchymal lung diseases of unknown etiology characterized by the presence of various degrees of inflammation and fibrosis 2.
- IIPs can be grouped into primary inflammatory disorders, fibrotic nonspecific interstitial pneumonia, and idiopathic pulmonary fibrosis 3.
- The new classification of idiopathic interstitial pneumonias published in 2013 distinguishes 6 major entities, including chronic fibrosing forms, acute/subacute forms, and smoking-related disorders 4.
Cryptogenic Organising Pneumonia
- Cryptogenic organizing pneumonia (COP) is a form of idiopathic interstitial pneumonia that results from the pulmonary reaction to various unidentified injuries 5.
- COP is usually subacute and does not manifest as severe disease, with patients maintaining sufficient respiratory function, and treatment with steroids is usually effective 5.
- Secondary organizing pneumonia is diagnosed when the triggering factor has been identified, and it is mainly caused by infections, toxic substance exposure, drugs, connective tissue diseases, malignancies, autoimmune diseases, bone marrow, or organ transplantation, and radiotherapy 5.
Diagnosis and Treatment
- Confident definitive diagnosis of the various IIPs requires dynamic interaction among clinicians, radiologists, and pathologists to arrive at a clinico-radiologic-pathologic diagnosis 2.
- High-resolution computed tomography plays an important role in the initial diagnosis, the assessment of disease extent, the likelihood of response to treatment and prognosis, and the assessment of complications 2.
- Lung transplantation is currently the only curative option for treatment, but many new antiproliferative and immunosuppressive agents are being used to effectively slow the progression of lung dysfunction 6.
- Treatment of IIPs can be grouped into primary inflammatory disorders, fibrotic nonspecific interstitial pneumonia, and idiopathic pulmonary fibrosis, with a practical approach to the treatment of these three patient groups 3.