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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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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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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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Symptom presentation also varies, ...