Original Article Histopathological features predictive of a clinical diagnosis of ophthalmic granulomatosis with polyangiitis (GPA)

Background: The limited form of Granulomatosis with Polyangiitis (GPA), formerly known as Wegener's Granulomatosis (WG) primarily involves the head and neck region, including the orbit, but is often a diagnostic challenge, particularly as it commonly lacks positive anti-neutrophil cytoplasm antibody (ANCA) titres or classical features on diagnostic orbital biopsies. The purpose of this study was to relate biopsy findings with clinical outcome and to determine which histopathological features are predictive of a clinical diagnosis of GPA. Methods: Retrospec- tive case series of 234 patients identified from the database of the UCL Institute of Ophthalmology Department of Eye Pathology as having had orbital biopsies of orbital inflammatory disorders performed between 1988 and 2009. Clinical records were obtained for the patients and analysed to see whether patients had GPA or not, according to a standard set of diagnostic criteria (excluding any histopathological findings). Biopsy features were then correlated with the clinical diagnosis in univariate and multivariate analyses to determine factors predictive of GPA. Results: Of the 234 patients, 36 were diagnosed with GPA and 198 with other orbital pathologies. The majority of biopsies were from orbital masses (47%). Histology showed a range of acute and chronic inflammatory pictures in all biop- sies, but the presence of neutrophils (P<0.001), vasculitis (P<0.001), necrosis (P<0.001), eosinophils (P<0.02) and macrophages (P=0.05) were significantly associated with a later clinical diagnosis of GPA. In a multivariate analysis, only tissue neutrophils (OR=3.6, P=0.01) and vasculitis (OR=2.6, P=0.02) were independently associated with GPA, in contrast to previous reports associating eosinophils and necrosis with the diagnosis. Conclusions: Neutrophil, eosinophil and macrophage infiltration of orbital tissues, together with vasculitis and necrosis, are all associated with a clinical diagnosis of GPA, but only neutrophil infiltration and vasculitis are independently associated with this diagnosis. These features may assist in the establishing the diagnosis of limited GPA among patients with early orbital disease, particularly in the absence of positive serum ANCA titres.