Pulmonary vascular inflammation may be seen in a variety of primary lung diseases, such as sarcoidosis, eosinophilic pneumonia, and hypersensitivity pneumonitis, and in the setting of various systemic diseases, including primary and secondary vasculitides, rheumatic autoimmune diseases, infectious processes, and lymphoproliferative disorders. This article concentrates on those entities in which the pathologic process may include pulmonary vasculitis: Wegener's granulomatosis (WG), Churg-Strauss syndrome (CSS), pulmonary capillaritis, giant cell arteritis (GCA), Takayasu's arteritis (TA), and Behçet's disease (BD). General principles of treatment of the vasculitides are reviewed.

Before discussing vasculitic processes in the lung, however, it is necessary to review the complexities and limitations of the current nomenclature systems for the systemic vasculitides in general. Definitive classification of the systemic vasculitides has been notoriously difficult, and much thought and energy has been put into developing systems by which these diseases may be adequately defined and distinguished.<sup>56 Hunder G.G., Arend W.P., Bloch D.A. , et al. The American College of Rheumatology 1990 criteria for the classification of vasculitis: Introduction Arthritis Rheum 1990 ;  33 : 1065-1067

Cliquez ici pour aller à la section Références, 59 Jennette J.C., Falk R.J., Andrassy K. , et al. Nomenclature of systemic vasculitides: Proposal of an international consensus conference Arthritis Rheum 1994 ;  37 : 187-192  [cross-ref]

Cliquez ici pour aller à la section Références</sup> At first glance, the classic descriptions of the various diseases seem specific enough for unique diagnoses. For example, CSS presenting as pulmonary infiltrates, asthma, atopy, upper airway inflammation, and eosinophilia would be readily distinguishable from TA presenting as fever, extremity claudication, hypertension, asymmetric blood pressure, and bruits in a young woman.

Nonetheless, whereas differentiating between classic examples of the disease entities may be straightforward, many patients do not manifest the entire panoply of symptoms, and others present clinical pictures that overlap two or more diagnoses. It is in these instances that the limitations of the current systems become evident.

Specific aspects of the systemic vasculitides that hamper the development of efficient diagnostic criteria or classification schemes include the following observations: (1) causative agents for these diseases have only rarely been recognized (e.g., hepatitis B virus, hepatitis C virus), (2) pathologic features and serologic markers in these diseases have limited specificity, (3) the histopathologic findings within organs are not homogeneous and may be in evolution, leading to false-negative or nonspecific biopsy findings, (4) each of the systemic vasculitides consists of a wide spectrum of manifestations and degrees of severity, and (5) many nonvasculitic diseases can mimic vasculitis. Some examples are endocarditis, cancer, drug toxicity and poisoning, coagulopathy, atrial myxoma, and multifocal mycotic or cholesterol emboli.