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40 years!
Last updated:
9/20/2023
Years published: 2006, 2010, 2013, 2018, 2023
NORD gratefully acknowledges O’Neil Green, MD, Critical Care Medicine and Pulmonology, Baystate Wing Hospital, for assistance in the preparation of this report.
Organizing pneumonia (OP) is a rare inflammatory lung disorder characterized by clinical symptoms such as flu-like illness as well as cough and shortness of breath with exertional activities. Wheezing and hemoptysis (blood when coughing) may occur rarely. OP refers to organized swirls of inflammatory tissue filling the small spherical units of the lungs called alveoli as well as the alveolar ducts. Individuals with OP experience inflammation of the bronchioles and alveolar lung spherical units simultaneously, which distinguishes it from other similar inflammatory lung disorders. Though the term pneumonia is used, OP is not an infection. It is a different disease from obliterative bronchiolitis which refers to scarring and narrowing of the small airways.
Several different known causes of OP have been identified, but most cases occur for no known reason (idiopathic). Idiopathic organizing pneumonia may also be called cryptogenic organizing pneumonia (COP).
Some people affected with this condition do not need treatment. When treatment is needed, corticosteroids, such as prednisone, are the most used medication. If the symptoms do not improve other treatment may be needed.
Since the first description in 1980 as bronchiolitis obliterans organizing pneumonia (BOOP), OP has been known by different names.
Symptoms of organizing pneumonia vary from person to person depending upon the specific type. For example, people with idiopathic OP have a flu-like illness, while people with OP associated with an underlying connective-tissue disorder have cough or shortness of breath. Some individuals with OP such as focal OP may have no apparent symptoms, while others may have severe respiratory distress as in acute, rapidly progressive OP.
Symptoms usually develop slowly over a few weeks or months. The most common symptom is a persistent, nonproductive cough. Some affected individuals develop a flu-like illness characterized by a sore throat, a general feeling of ill health (malaise), weight loss and fatigue. Eventually, shortness of breath, especially from exertional activities may develop. The shortness of breath and cough may become progressively worse.
Individuals with OP may develop small crackling or rattling sounds in the lung (crackles or rales) that are apparent upon physical examination. In rare cases affected individuals may experience chest pain, joint pain (arthralgia), night sweats or coughing up blood (hemoptysis).
A rapidly progressive form of OP exists that can progress from symptom onset to acute respiratory failure in only a few days. This form of OP may be associated with an underlying fibrotic process.
In most cases, the cause of OP is unknown and is referred to as idiopathic OP. Causes of OP include radiation therapy; exposure to certain fumes or chemicals, exposure to birds, post respiratory infections, after organ transplantation; and from more than 35 medications. Systemic disorders associated with OP include connective-tissue diseases, immunological disorders and inflammatory bowel disease. Organizing pneumonia has also been seen in association with lung abscess, lung cancer and lymphoma. Importantly, the OP lesion is seen as a co-existent pathologic finding in individuals with idiopathic pulmonary fibrosis (IPF) and in these situations, the primary pathologic disorder is the IPF, and the secondary process is OP.
Organizing pneumonia affects males and females in equal numbers. It develops in individuals between 40-60 years old, but the disorder may affect individuals of any age. Organizing pneumonia is estimated to account for 5 to 10% of the chronic infiltrative lung disease in the United States. Organizing pneumonia has been reported throughout the world.
A diagnosis of OP may be made based upon a clinical evaluation, a detailed patient history, identification of characteristic findings and specialized tests such as x-ray studies, especially a high-resolution chest computed tomography (HRCT), pulmonary function studies that includes a diffusing capacity test and often a lung biopsy for microscopic tissue analysis. Lung biopsy may infrequently be made via conventional transbronchial biopsy, transbronchial cryobiopsy which is newer and recovers a larger bit of tissue, or in selected cases, open lung biopsy. The HRCT scan often shows “ground glass” densities that are often triangular with the base of the triangle along the chest wall and the airways can often be seen in the ground-glass opacities. There are other less common findings such as inflammation along the air tubes or bronchi as well as single spots or nodules which are sometimes confused with malignancy, or the so-called ‘atoll’ spots which are areas of inflammation with central darker areas on HRCT.
Treatment
In some patients, the symptoms of OP may resolve without treatment, especially the post breast radiation-type. In some mild cases such as individuals without symptoms or who have non-progressive disease, the process can be monitored and treated later if necessary. Many individuals with OP require treatment with the anti-inflammatory, corticosteroid medication, usually in the form of prednisone. This therapy often results in dramatic improvement with resolution of symptoms within days or weeks. In some people, the OP may recur as the dose is decreased, but the OP will respond to an additional course of treatment. There is a role for the use of clarithromycin, an antibiotic, in patients with mild disease. Clarithromycin has an anti-inflammatory effect and is not being used to treat an infection. A recent study of clarithromycin in addition to prednisone for 12 weeks to treat organizing pneumonia caused by radiation, showed no advantage over prednisone alone for 24 weeks.
The rapidly progressive form of OP is treated with intravenous corticosteroid medication and sometimes with cyclophosphamide (Cytoxan). Individuals with secondary OP may improve after treating the underlying condition. Additional treatment is symptomatic and supportive.
For individuals who do not respond to steroid therapy, other agents have been used including erythromycin in the form of azithromycin, and mycophenolate mofetil (CellCept). These agents have been beneficial to individuals with OP on a case-by-case basis (anecdotally) reported in the medical literature. However, research is needed to determine the long-term safety and effectiveness of these potential treatment options for individuals with OP.
In rare cases, lung transplantation may be necessary for individuals with OP who do not respond to standard treatment options.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/for-patients-and-families/information-resources/info-clinical-trials-and-research-studies/
For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com
For more information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
TEXTBOOKS
Mason RJ, Broaddus VC, Murray JF, Nadel JA. eds. Murray and Nadel’s Textbook of Respiratory Medicine. 4th ed. Elsevier Saunders. Philadelphia, PA; 2005:1297-1300.
Bennett JC, Plum F., eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA: W.B. Saunders Co; 1996:394-5.
Fishman AP., ed. Pulmonary Diseases and Disorders, 2nd ed. New York, NY: McGraw-Hill Book Company; 1988: 739-40.
JOURNAL ARTICLES
Griff S, Schonfeld N, Ammenwerth W, et al. Diagnostic yield of transbronchial cryobiopsy in non-neoplastic lung disease: a retrospective case series. BMC Pulm Med. 2014; 14: 171.
Epler GR. Bronchiolitis obliterans organizing pneumonia, 25 years: a variety of causes, but what are the treatment options? Expert Rev Respir Med. 2011 Jun;5(3):353-361.
Stover DE, Mangino D. Macrolides: a treatment alternative for bronchiolitis obliterans organizing pneumonia? Chest. 2005; 128:3611-7.
Oymak FS, Demirbas HM, Mavili E, et al., Bronchiolitis obliterans organizing pneumonia. Clinical and roentgenological features in 26 cases. Respiration. 2005; 72:254-62.
Lazor R. Cryptogenic organizing pneumonia. Rev Pneumol Clin. 2005; 61:193-202.
Husain SJ, Irfan M, Zubairi AS, Salahuddin N. Rapidly-progressing bronchiolitis obliterans organizing pneumonia. Singapore Med J. 2004; 45:283.
Al-Saghir AH, Al-Mobeireek AF. Bronchiolitis obliterans organizing pneumonia. Saudi Med J. 2004; 25:557-65.
Cordier JF. Cryptogenic organizing pneumonia. Clin Chest Med. 2004; 25:727-38.
Cordier JF. Bronchiolitis obliterans organizing pneumonia. Semin Respir Crit Care Med. 2000; 21:135-46.
Cazzato S, Zompatori M, Baruzzi G, et al. Bronchiolitis obliterans-organizing pneumonia: An Italian experience. Respir Med. 2000 Jul;94(7): 702-8.
Radzikowska E, Wiatr E, Langfort R et al. Cryptogenic organizing pneumonia – Results of treatment with clarithrymycin versus corticosteroids – Observational study. PloS One. 2017; 12(9): e0184739
Petitpierre N, Cottin V, Marchand-Adam S et al. A 12-week combination of clarithrymycin and prednisone compared to a 24-week prednisone alone treatment in cryptogenic and radiation-induced organizing pneumonia. Sarcoidosis Vasc Diffuse Lung Dis. 2018;35(3):230-238
INTERNET
Khan AN. Imaging in Bronchiolitis Obliterans Organizing Pneumonia. Medscape Updated: March 16, 2021. Available at: https://www.emedicine.com/radio/topic117.htm Accessed August 10, 2023.
Cordier JF, Costabel U, du Bois RM. Cryptogenic Organizing Pneumonia. Orphanet Encyclopedia. Last Update: October 2022. Available at: https://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=1302#:~:text=A%20rare%20form%20of%20idiopathic,no%20etiological%20agent%20is%20found. Accessed August 10, 2023.
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