Introduction: Granulomatosis with polyangiitis (GPA) is a rare, ANCA-associated, systemic disease characterized by necrotizing small and medium vessel vasculitis of unknown etiology associated with granulomatous inflammation affecting the renal, pulmonary, upper airways, ocular systems and other tissues. Histological proof of the granulomatosis with polyangiitis (GPA) can be obtained by biopsy of clinically involved sites. The main purpose of this study was to examine histopathological changes in non-renal biopsies from patients with established diagnosis of GPA and evaluated the histological confirmation at diagnosis of this disease.
Material and methods: A retrospective analysis was performed in patients with GPA diagnosed and treated in clinics of the University Clinical Center (UCK) in Gdansk in 1988–2009.
Results: In the analyzed group of GPA patients the histopathological examination of biopsies taken from involved tissues (except kidney) was performed in 60% of patients. Thirty-six out of 93 biopsies (39%) were diagnosed as typical of GPA, 10 (10.7%) were suggestive and 51 (54.8%) were non-specific. Considering all biopsies, the diagnosis was confirmed in 24 patients (57% of patients in whom biopsies were taken). Epitheloid cell granulomas were present in 33 biopsies (43%), characteristic necrosis in 27 biopsies (35%), small vessel vasculitis in 18 biopsies (23%), while multinucleated giant cells were identified only in 9 biopsies (12%).
Conclusions: Histopathological examination of the affected tissues remains the gold standard of the diagnosis of GPA. Its usefulness increases, particularly in ANCA-negative patients, in the initial phase of the disease, or in patients with atypical clinical presentation. In many cases, it is necessary to repeat biopsy to establish the diagnosis. The role of the histopathological examination seems to be particularly important when ANCA is negative or clinical symptoms are atypical of GPA.