What are the indications that a patient has cryptogenic organizing pneumonia (COP)?

From the Guidelines

Cryptogenic organizing pneumonia (COP) is indicated by a combination of clinical, radiological, and histopathological features, including subacute illness with symptoms developing over weeks to months, persistent dry cough, progressive dyspnea, and characteristic radiological findings such as patchy consolidation and the "reverse halo" sign, as described in the British Thoracic Society guideline 1. The clinical presentation of COP typically includes a subacute illness with symptoms developing over weeks to months, including:

• Persistent dry cough
• Progressive dyspnea (shortness of breath)
• Low-grade fever
• Malaise
• Weight loss Physical examination may reveal inspiratory crackles on lung auscultation, while pulmonary function tests often show a restrictive pattern with reduced diffusion capacity. Radiologically, COP has distinctive features, including:
• Chest X-rays showing bilateral patchy alveolar opacities
• CT scans demonstrating peripheral or peribronchial consolidations, ground-glass opacities, and the characteristic "reverse halo" or "atoll sign" (a central ground-glass opacity surrounded by a ring of consolidation) 1. Laboratory findings are nonspecific but may include elevated inflammatory markers like C-reactive protein and erythrocyte sedimentation rate. The definitive diagnosis requires histopathological confirmation through lung biopsy showing organizing pneumonia pattern with preservation of lung architecture, characterized by fibroblastic plugs (Masson bodies) within alveolar ducts and alveoli. It is essential to exclude other causes of organizing pneumonia, such as infections, drug reactions, connective tissue diseases, or exposure to toxins, to establish a diagnosis of COP 1.

From the Research

Indications of Cryptogenic Organizing Pneumonia (COP)

The indications that a patient has COP include:

• Clinical presentations such as cough, sputum, and exertional dyspnea 2
• Radiological findings including consolidation in the inferior lobes on thoracic computed tomography, scattered speckled, patchy and trabecular shadows over both lung fields on high-resolution computerized tomography, and multiple patchy alveolar opacities 3, 2, 4
• Histological findings of polypoid growths of granulation tissue within respiratory bronchioles, small airways, and alveolar spaces 2
• Response to glucocorticoid therapy, with a high overall response rate 2, 5
• Definitive diagnosis based on a suggestive clinical radiological presentation, demonstration of the characteristic pathological pattern at lung histopathology, and exclusion of possible causes 4

Common Symptoms

Common symptoms of COP include:

• Cough, which was present in 88.2% of patients in one study 3
• Dyspnea, which was a common symptom in multiple studies 2, 4, 5
• Malaise, fever, and bilateral alveolar infiltrates, which were also common findings 5

Radiological Findings

The main radiological presentations of COP include:

• Consolidation in the inferior lobes on thoracic computed tomography 3
• Scattered speckled, patchy and trabecular shadows over both lung fields on high-resolution computerized tomography 2
• Multiple patchy alveolar opacities, which is the typical pattern 4
• Solitary focal nodule or mass, and diffuse infiltrative opacities, which are less common patterns 4

Diagnosis and Treatment

Diagnosis of COP is typically made by:

• Open lung biopsy 3
• Transbronchial biopsy 3, 4
• Video-assisted thoracoscopic surgery biopsy 3, 2 Treatment of COP usually involves corticosteroid therapy, which is rapidly effective but may have a high relapse rate on reducing or stopping treatment 3, 2, 4, 5, 6