From the Guidelines
Treatment for cryptogenic organizing pneumonia (COP) should begin with oral corticosteroids, specifically prednisone at 0.5-1 mg/kg/day, due to its excellent response rate and better prognosis compared to other idiopathic interstitial pneumonias (IIPs) 1.
Diagnosis and Presentation
Idiopathic interstitial pneumonias (IIPs) are a group of diffuse parenchymal lung diseases of unknown cause, with cryptogenic organizing pneumonia (COP), formerly known as bronchiolitis obliterans organizing pneumonia (BOOP), being one specific type. Patients with COP typically present with a subacute illness of relatively short duration, with variable degrees of cough and dyspnea 1.
- Key diagnostic features include:
- Patchy and often migratory consolidation in a sub-pleural, peribronchial, or bandlike pattern on HRCT
- Ground-glass opacity and perilobular opacities
- Reversed halo (or atoll) sign
- Small unilateral or bilateral pleural effusion in 10-30% of patients
Treatment Approach
The majority of patients recover completely with oral corticosteroids, but relapse is common, highlighting the need for careful monitoring and follow-up 1.
- Initial treatment: prednisone at 0.5-1 mg/kg/day (usually 40-60 mg daily) for 1-3 months, followed by a gradual taper over 6-12 months total
- Steroid-resistant cases: consider adding immunosuppressants like cyclophosphamide, azathioprine, or mycophenolate mofetil
- Macrolide antibiotics such as clarithromycin or azithromycin can be considered as steroid-sparing agents
- Supportive care: supplemental oxygen if hypoxemic, pulmonary rehabilitation, and vaccination against influenza and pneumococcal disease
Prognosis and Follow-Up
COP differs from other IIPs like idiopathic pulmonary fibrosis in its excellent response to steroids and better prognosis 1.
- Regular follow-up with pulmonary function tests and imaging is essential to monitor treatment response and detect relapses, which occur in approximately 15-25% of cases
- The pathophysiology involves an inflammatory response to lung injury with proliferation of granulation tissue in small airways and alveolar spaces, forming characteristic "Masson bodies" that obstruct airflow 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.
- Cryptogenic organizing pneumonia (COP) is a form of idiopathic interstitial pneumonia that results from the pulmonary reaction to various unidentified injuries 3.
- IIPs can be grouped into primary inflammatory disorders, fibrotic nonspecific interstitial pneumonia, and idiopathic pulmonary fibrosis for treatment purposes 4.
Clinical Features and Diagnosis
- COP is characterized by dyspnea and cough, with multiple patchy alveolar opacities on pulmonary imaging 5.
- Definite diagnosis of COP is obtained by the finding of buds of granulation tissue in the distal airspaces at lung biopsy 5.
- High-resolution computed tomography plays an important role in the initial diagnosis, assessment of disease extent, likelihood of response to treatment and prognosis, and assessment of complications 2.
Treatment and Prognosis
- Corticosteroid treatment is rapidly effective for COP, but relapses are common on reducing or stopping treatment 5.
- Lung transplantation is currently the only curative option for treatment of IIPs, but many new antiproliferative and immunosuppressive agents are being used to effectively slow the progression of lung dysfunction 6.
- The classical form of COP usually has a good prognosis, but specific forms of OP (e.g., the cicatricial variant or acute fibrinous type) have distinct clinical and histological features, require higher doses of immunosuppressive drugs, and have a worse prognosis 3.