Purpose of review: Pulmonary vascular involvement and the resulting clinical manifestations are prominent in several of the idiopathic systemic small vessel vasculitis syndromes. This group of syndromes, often referred to as the antineutrophil cytoplasmic antibody-associated vaculitis syndromes, is composed of the Churg–Strauss syndrome, Wegener's granulomatosis, microscopic polyangiitis, and several organ specific subsets of the latter. The former three syndromes form the basis of this review.
Recent findings: Because the presenting signs and symptoms are variable and because these are uncommon disorders, the clinical manifestations in different age groups, ethnic groups, sexes, stage of disease among others have been documented by way of a number of case series and case reports. The role of the antineutrophil cytoplasmic antibody in these disorders is being clarified. In diagnosis, the usefulness of the test depends on the sensitivity and specificity of testing in the population being studied. In pathogenesis, the antineutrophil cytoplasmic antibody may be causative or may merely be associated with the clinical manifestations.
Summary: These disorders, although distinctive, are often difficult to diagnose and commonly pose a perplexing clinical scenario for the clinician. A thorough history, physical examination, and a high index of suspicion is mandatory if these entities are to be recognized expeditiously.