Pulmonary vasculitis: CT features.

The pulmonary vasculitides are a heterogeneous group of inflammatory disorders that may be primarily localized to the pulmonary vasculature or be systemic in nature. The primary pulmonary vasculitides usually affect small vessels, whereas the systemic vasculitides can involve any size pulmonary vessels. For all types of vasculitis, there is a high degree of overlap within groups in regard to their appearance at computed tomography (CT). The most common CT findings are the result of either diffuse or focal pulmonary hemorrhage, are nonspecific, and include ground-glass opacity, consolidation, and small centrilobular nodules. Therefore, the CT findings must be considered in concert with the history, physical examination, and laboratory examination when a specific diagnosis is sought. This review will discuss the typical CT features of both the systemic and the primary pulmonary vasculitides, drawing a distinction where CT is helpful in differentiating among the various causes.