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Vasculitis affecting the lung is exceptionally uncommon in children. The presentation may vary from mild, chronic respiratory symptoms to an acute, catastrophic, life-threatening pulmonary hemorrhage. When symptoms are indolent, diagnosis may be delayed by months or years. Early, aggressive treatment is imperative in cases of pulmonary vasculitis. Cumulative lung damage due to ongoing inflammation can lead to pulmonary fibrosis.

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Epidemiology

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The epidemiology of pulmonary vasculitis is varied, depending on the underlying disease process. (Vasculitic diseases are discussed in more detail in Chapter 203.) In general, the autoimmune diseases affect females more than males in adulthood. In childhood, the gender discrepancy may be less. Some vasculitic syndromes can affect African Americans and Asians with greater frequency and with greater severity of disease than Caucasians. Age of onset in children is variable as well. For example, the mean age of onset of Wegener granulomatosis (WG) in children is 13 years, with reports of patients presenting before their first birthday.1

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Pathophysiology

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Vasculitis signifies blood vessel wall inflammation. Neutrophils infiltrate the vessel walls and damage the endothelial cell layer. Vessel walls thicken and result in luminal narrowing. Fibrinous thrombi may further occlude capillary blood flow.2 Over several weeks to many months, inflammation of the blood vessel wall leads to fibrosis. Simultaneously, inflammation involves the pulmonary interstitium and leads to fibrosis. The end result is destruction of normal lung architecture with decreased gas-exchange capacity.2

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The etiology of the diseases that result in pulmonary vasculitis is unknown. The collagen vascular and granulomatous diseases are felt to be complex genetic conditions. Numerous genes, most of which are currently undefined, may lead to a predisposition to develop a specific autoimmune condition. Environmental factors, such as exposure to viruses, may serve as triggers to set off the cascade of autoimmunity.

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Clinical Features and Differential Diagnosis

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A child with pulmonary vasculitis may present with indolent symptoms, including fatigue, fever, weight loss, failure to thrive, pallor, decreased appetite, or irritability. Respiratory symptoms may include cough, dyspnea, chest tightness, or hemoptysis. Some present with acute symptoms, including massive pulmonary hemorrhage, that can result in respiratory failure and cardiovascular collapse. The slow, indolent presentation of mild intermittent respiratory symptoms as seen in the case of pulmonary capillaritis can lead to misdiagnosis (atypical asthma) and delayed diagnosis (Fig. 517-1).3 The child presenting with frank hemoptysis secondary to bleeding of medium- or large-sized vessels is generally diagnosed more promptly. The possibility of pulmonary vasculitis should be raised in any child who has the triad of respiratory symptoms, anemia, and bibasilar infiltrates on chest x-ray.4

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Figure 517-1.
Graphic Jump Location

Pulmonary capillaritis. Chest radiograph of a 3-year-old girl with pulmonary vasculitis shows bibasilar patchy opacities.

(Courtesy of Amisha J. Shah, Pittsburgh, PA.)

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Symptom presentation also ...

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