(See also Overview of Idiopathic Interstitial Pneumonias.)
Lymphoid interstitial pneumonia is a form of idiopathic interstitial pneumonia. It can occur in children, usually those infected with the human immunodeficiency virus (HIV). Lymphoid interstitial pneumonia can also occur in adults, often those with autoimmune disorders such as plasma cell disorders, Sjögren syndrome, Hashimoto thyroiditis, rheumatoid arthritis, and systemic lupus erythematosus (lupus). Women and girls are more commonly affected. Average age of affected adults is 54.
Diagnosis requires chest x-ray, computed tomography (CT), and pulmonary function testing. Pulmonary function tests usually show a decrease in the amount of air the lungs can hold. Doctors often do bronchoscopy and wash segments of the lung with a salt-water solution and then collect the washings (bronchoalveolar lavage) for testing.
Blood tests may reveal abnormalities in their blood proteins that can help establish the diagnosis. This blood protein test is particularly useful in children and may be adequate to establish the diagnosis. If not, and for all adults, lung biopsy is usually necessary.
The prognosis is difficult to predict. The disorder may resolve on its own or after treatment, or it may progress to lung fibrosis or lymphoma (a cancer). One half to two thirds of people are alive 5 years after diagnosis.
Treatment is with corticosteroids, cytotoxic drugs (such as azathioprine or cyclophosphamide), or both, but the effectiveness of these drugs is unknown.