Organizing pneumonia

by Katherina Baranova MD and Matthew J. Cecchini MD PhD FRCPC
May 25, 2022


What is organizing pneumonia?

Organizing pneumonia is a type of acute lung injury. Organizing pneumonia often only affects parts of the lung while other parts remain normal and healthy.

What are the symptoms of organizing pneumonia?

Symptoms of organizing pneumonia can include dry cough, difficulty breathing, fever, and weight loss.

What causes organizing pneumonia?

Organizing pneumonia is a pattern of acute lung injury that has many causes. The most common causes of organizing pneumonia include infections with bacteria, viruses, fungi, and parasites, drugs, radiation to the chest, connective tissue disorders and inflammatory disorders, and aspiration of stomach contents into the lungs.

Your doctor will consider your symptoms, medical history, recent travel, and medications taken to determine the cause of organizing pneumonia. If no cause can be found, a diagnosis of “cryptogenic organizing pneumonia” is made. Cryptogenic organizing pneumonia is generally associated with a good prognosis and responds well to corticosteroids, such as prednisone.

Tests performed to determine the cause of organizing pneumonia?

If your doctor suspects that you have organizing pneumonia, they may perform a procedure called a biopsy which removes a small tissue sample for examination by a pathologist. Your pathologist will look at the tissue sample under the microscope and may order additional tests to help determine the cause.

These additional tests may include a special stain called Grocott’s methenamine silver stain (also called GMS) to look for fungal micro-organisms and immunohistochemistry to look for specific types of viruses. If no specific cause can be found, your pathologist will describe the changes seen in your biopsy and will suggest that your doctor consider these changes along with other information about you in order to make a final diagnosis. This combination of information is called clinical correlation.

What does organizing pneumonia look like under the microscope?

When a sample of lung tissue is examined under the microscope, a collection of specialized cells called fibroblasts can be seen within the air spaces called alveoli. Specialized inflammatory cells such as lymphocytes may also be seen in the walls of the air spaces.

Groups of fibroblasts within the affected areas of the lung prevent air from filling the alveoli. As a result, patients with organizing pneumonia can feel short of breath. Radiology reports often describe these areas of the lung as ground-glass opacities.

A+ A A-