Lymphoid interstitial pneumonia

Lymphoid interstitial pneumonia (lymphocytic interstitial pneumonitis) is characterized by lymphocytic infiltration of the interstitium of the alveoli and air spaces.

The cause of lymphoid interstitial pneumonia is unknown. It is most common in children with HIV infection and people of any age with autoimmune diseases. Symptoms of lymphoid interstitial pneumonia include cough, progressive dyspnea, and wheezing. Diagnosis is by history, physical examination, imaging studies, pulmonary function tests, and histologic examination of a lung biopsy. Treatment of lymphoid interstitial pneumonia includes glucocorticoids and/or cytotoxic agents, although the effectiveness is unknown. Five-year survival is 50 to 66%.

Lymphoid interstitial pneumonia is a rare disorder characterized by infiltration of the alveoli and alveolar septa with small lymphocytes and variable numbers of plasma cells. Noncaseating granulomas may be present but are usually rare and inconspicuous.

Lymphoid interstitial pneumonia is the most common cause of lung disease after Pneumocystis carinii infection in HIV-positive children and is the pathology that predicts the development of AIDS in about half of them. Less than 1% of cases of lymphoid interstitial pneumonia occur in adults, who may or may not be HIV-infected. Women are more often affected.

[ 1 ]

What causes lymphoid interstitial pneumonia?

The cause of the disease is considered to be an autoimmune process or a non-specific reaction to infection with Epstein-Barr viruses, HIV or others. Evidence of autoimmune etiology is a frequent association with Sjogren's syndrome (25% of cases) and other systemic processes (for example, systemic lupus erythematosus, rheumatoid arthritis, Hashimoto's disease - 14% of cases). An indirect sign of viral etiology is a frequent association with immunodeficiency states (HIV / AIDS, combined variable immunodeficiency, agammaglobulinemia, which is observed in 14% of cases) and the detection of Epstein-Barr virus DNA and HIV RNA in the lung tissue of patients with lymphoid interstitial pneumonia. According to this theory, lymphoid interstitial pneumonia is an extremely pronounced manifestation of the normal ability of the lymphoid tissue of the lung to respond to inhaled and circulating antigens.

Symptoms of lymphoid interstitial pneumonia

In adults, lymphoid interstitial pneumonia causes progressive shortness of breath and cough. These symptoms of lymphoid interstitial pneumonia progress over months or, in some cases, years; the average age of onset is 54 years. Less common symptoms include weight loss, fever, arthralgia, and night sweats.

In children, lymphoid interstitial pneumonia causes bronchospasm, cough, and/or respiratory distress syndrome and developmental disabilities, usually appearing between 2 and 3 years of age.

Physical examination reveals moist rales. Hepatosplenomegaly, arthritis, and lymphadenopathy are rare and suggest an associated or alternative diagnosis.

Diagnosis of lymphoid interstitial pneumonia

The diagnosis is established by analyzing the anamnesis data, physical examination, radiological studies and pulmonary function tests and is confirmed by the results of histological examination of biopsy material.

Chest radiography reveals linear or focal opacities and increased pulmonary markings, predominantly in the basal regions, as well as nonspecific changes seen in other lung infections. Alveolar opacities and/or honeycombing may be seen in more advanced cases. High-resolution CT helps to establish the extent of the lesion, evaluate the anatomy of the lung root, and identify pleural involvement. Characteristic changes include centrilobular and subpleural nodules, thickened bronchovascular bands, ground-glass opacities, and, rarely, diffuse cystic changes.

Pulmonary function tests reveal restrictive changes with decreased lung volumes and diffusion capacity for carbon monoxide (DL^) while maintaining flow characteristics. Marked hypoxemia may be present. Bronchoalveolar lavage should be performed to exclude infection and may show an increased lymphocyte count.

Approximately 80% of patients have serum protein abnormalities, usually polyclonal gammopathy and, particularly in children, hypogammaglobulinemia, but the significance of these changes is unknown. These findings are usually sufficient to confirm the diagnosis in HIV-positive children. In adults, the diagnosis requires demonstration of dilated alveolar septa with infiltration by lymphocytes and other immunocompetent cells (plasma cells, immunoblasts, and histiocytes). Germinal centers and multinucleated giant cells with noncaseating granulomas may also be seen. Infiltrates occasionally develop along the bronchi and vessels, but more commonly the infiltration extends along the alveolar septa. Immunohistochemical staining and flow cytometry should be performed to differentiate lymphoid interstitial pneumonia from primary lymphomas; In lymphoid interstitial pneumonia, the infiltration is polyclonal (B- and T-cell), whereas the lymphomatous infiltrate is monoclonal.

[ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ]

Treatment of lymphoid interstitial pneumonia

Treatment of lymphoid interstitial pneumonia involves the use of glucocorticoids and/or cytotoxic agents, similar to many other IBLBP options, but the effectiveness of this approach is unknown.

What is the prognosis for lymphoid interstitial pneumonia?

Lymphoid interstitial pneumonia is a poorly understood lung disease, as well as its course and prognosis. The prognosis may be related to the severity of changes on radiography, which may correlate with a greater severity of the immune response. Spontaneous resolution, relief with glucocorticoid or other immunosuppressive therapy, progression with the development of lymphoma or pulmonary fibrosis and respiratory failure may occur. Five-year survival is 50 to 66%. Common causes of death are infection, development of malignant lymphomas (5%), and progressive fibrosis.