Update on cryptogenic organizing pneumonia

Abstract

Cryptogenic organizing pneumonia (COP) is a form of idiopathic interstitial pneumonia that results from the pulmonary reaction to various unidentified injuries. Secondary organizing pneumonia is diagnosed when the triggering factor has been identified; it is mainly caused by infections, toxic substance exposure, drugs, connective tissue diseases, malignancies, autoimmune diseases, bone marrow, or organ transplantation, and radiotherapy. There has been an increase in the number of reports of drug-induced organizing pneumonia (OP). New biological therapies, interferon, monoclonal antibodies, anti-interleukin antibodies, and PD1/PDL-1 inhibitors may induce this specific pulmonary reaction. The classical form of COP is usually subacute and does not manifest as severe disease. Patients maintain sufficient respiratory function, and treatment with steroids is usually effective. Several 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. In the era of administering steroid-sparing therapies for the treatment of interstitial lung diseases, connective tissue dases, and other conditions, it is important to emphasize this type of therapy for patients with COP.

Keywords: acute fibrinous organizing pneumonia; cicatrices organizing pneumonia; clarithromycin; cryptogenic organizing pneumonia; prednisone; secondary organizing pneumonia.

Figure 1

Chest X-ray of OP. Bilateral opacities localized in the peripheral parts of the both lungs.

Figure 2

High resolution computed tomography scan of a patient with COP. Bilateral ground glass opacities with associated peripheral consolidations forming an atoll sign.

Figure 3

High resolution computed tomography scan of a patient with COP. Bilateral nodular consolidations.

Figure 4

High resolution computed tomography scan of a patient with COP. Massive bilateral opacities with presence of air bronchogram and accompanying ground glass opacities on the right lung.

Figure 5

High resolution computed tomography scan of a patient with SOP in the course of dermatomyositis. In both lungs evidence of GGO with patchy distribution and parenchymal banding with “arcade” sign typical of OP. Status post lung biopsy on the right side.

Figure 6

HRCT scan. Etanercept induced AFOP, in patient with rheumatic arthritis and pulmonary fibrosis. Bilateral consolidations with air bronchogram, interlobular septa thickening, and ground glass opacities predominated in the peripheral parts of both lungs.

Figure 7

Histological image of organizing pneumonia (H-E). Alveoli filled with loose tissue forming polypoid formations extending into the respiratory tracts with a small diffuse inflammatory infiltrate in the interalveolar spaces.