ADVERTISEMENT

Clinical features and diagnosis of small-vessel vasculitis

November 1, 2012|Cleveland Clinic Journal of Medicine
Carol Langford, MD, MHS
Author and Disclosure Information

Carol Langford, MD, MHS
Director, Center for Vasculitis Care and Research, Department of Rheumatic and Immunologic Disease, Cleveland Clinic, Cleveland, OH

Correspondence: Carol Langford, MD, MHS, Department of Rheumatic and Immunologic Disease, Cleveland Clinic, 9500 Euclid Ave., A50, Cleveland, OH 44195; langfoc@ccf.org

Dr. Langford reported that she has no financial interests or relationships that pose a potential conflict of interest with this article.

This article was developed from an audio transcript of Dr. Langford’s presentation at the “New Directions in Small-Vessel Vasculitis: ANCA, Target Organs, Treatment, and Beyond” symposium held at Cleveland Clinic on May 4, 2011. The transcript was formatted and edited by Cleveland Clinic Journal of Medicine staff for clarity and conciseness, and was then reviewed, revised, and approved by Dr. Langford.

ABSTRACTVasculitis is inflammation of the blood vessel. Granulomatosis with polyangiitis (GPA), microscopic polyangiitis, and eosinophilic GPA are three small-vessel vasculitic diseases that share certain features, but also have important differences. Distinguishing these entities may influence the diagnostic approach, treatment decisions, and outcomes. Circulating antineutrophil cytoplasmic antibodies (ANCA) characterize all three diseases, although their immunofluorescence patterns and target antigen specificities differ. While the presence of ANCA can suggest these diagnoses, the diseases are best viewed as separate entities, each defined by specific clinical and histologic characteristics.

DIFFERENTIATION

Despite similarities, GPA, MPA, and EGPA are phenotypically unique. Because of differences in management, relapse risk, and outcome, differentiation is important. Several features can help distinguish these three small-vessel vasculitic diseases (Table). For example, upper airway disease, which tends to be necrotizing and destructive in GPA, is allergic in EGPA and absent in MPA. Lung disease in MPA tends to be pulmonary hemorrhage, which also can be seen in GPA. In GPA, however, nodular disease that may be cavitary is more common. Asthma is the predominant pulmonary feature in EGPA, although parenchymal nodules and hemorrhage also can be seen. While glomerulonephritis is typical in GPA and MPA, it occurs to a much lesser degree in EGPA. Cardiac features have particular importance in EGPA.

A key histologic difference between GPA and MPA is the presence of granulomatous inflammation in GPA and its absence in MPA under the current nomenclature system.9 Granulomatous inflammation can be seen in EGPA, but it is usually accompanied by eosinophils, which are less likely to be present in GPA and MPA.

The predominance of the ANCA immunofluorescence pattern and target antigen differs between GPA and MPA, with ANCA positivity occurring in 38% of patients with EGPA.13

SUMMARY

Conceptualizing vasculitic disease based on vessel size can be useful, but it is not an absolute definition. Although GPA, MPA, and EGPA predominantly affect small- to medium-sized vessels, these disease entities are phenotypically unique, with both shared features and differences. Common to all three entities is the potential for organ- and life-threatening manifestations, particularly involving the lungs, kidneys, nerves, gastrointestinal tract, and heart. All three entities need aggressive immuno suppression for severe disease. Recognition of these entities and the distinctions among them can guide the approach to diagnosis, treatment, and future outcomes.

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT