Background
Pulmonary capillaritis is an inflammatory condition that causes the destruction of the tiny blood vessels that surround the air sacs, called capillaries. This inflammation is associated with an increased number of neutrophils (a type of immune cell) in the capillary walls and surrounding tissue followed by death of the cells in the capillary walls (necrosis).
Symptoms
The symptoms can be acute, but are often slow in developing. Commonly, these children are anemic, experience exercise limitations, and have shortness of breath (dyspnea). Other symptoms include low oxygen levels in the blood (hypoxemia), cough, and abnormal chest x-rays. Some children will cough up blood or bloody mucus, but this is not always seen because some children swallow the secretions.
Diagnosis
Chest x-rays will show a ‘butterfly or batwing’ appearance of symmetric airspace opacities (lighter areas in the lung image) in most cases of alveolar hemorrhage, but some will have the opacities on one side or in an irregular pattern. A high-resolution CT scan is a more sensitive test that shows patchy ground-glass opacities and consolidation due to the blood filling up the air sacs. If the condition is chronic, septal thickening and nodular opacities can be seen. It can indicate capillaritis if small fluffy opacities are seen in the middle of the lobes around blood vessels. A biopsy is often used to confirm this diagnosis.
Capillaritis is often associated with other vascular disorders including, but not limited to, Wegener’s granulomatosis, microscopic polyangiitis, and Goodpasture’s disease.
Treatment
Pulmonary capillaritis must be treated aggressively. If left untreated, the inflammation causes damage and fibrosis of the lung tissue and is associated with high morbidity and mortality. The goal of the treatment is to cause remission of the symptoms. Current therapy includes high dose corticosteroids, cyclophasamide, and/or IV immunoglobulin. Once remission has been obtained, it is maintained with low-dose prednisone and either azathioprine or methotrexate, which suppress the immune system.
Prognosis
Historically, this diagnosis had a poor prognosis with mean survival of under 3 years. However, as treatments and our understanding improve, the survival rate has improved to over 80%.