AB0681 Biopsy results from patients with suspected granulomatosis with polyangiitisin a decade (2005–2015). aleatorised sample analysis of clinicopathological correlation
Authors: L.F. Flores-Suarez, H. Echeagaray, G. Tona-Acedo, R.M. Rivera-Rosales, N. Ruiz, A. Castorena-Maldonado
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> The diagnostic yield of airway biopsies in granulomatosis with polyangiitis (GPA) is usually less than 50%. <h3>Objectives</h3> To review the histologic diagnostic yield of airway biopsies sent with a suspected GPA diagnosis in a single-centre devoted to respiratory diseases by use of previously published criteria. Also, to know the interobserver variability among in-house pathologists, correlate signs and symptoms with GPA positive histologic findings, and with additional paraclinical data, apply the algorithm proposed by the European Medical Agencies (EMA) to know if a higher number of biopsies confidently supported a GPA diagnosis. <h3>Methods</h3> From 137 airways biopsies during a decade (2005–2015), fifty were randomly selected for the second review by an expert pathologist. Thereafter, with the incorporation of antineutrophil cytoplasm autoantibodies (ANCA) the EMA algorithm was applied. Demographic data were descriptively analysed, and results expressed according to their distribution. Categorical data, expressed in percentages, were analysed with χ<sup>2</sup> test and variance analysis. The associations of independent variables were analysed with one-tail exact Fisher test. Simple logistic regression was used for variable associations. The interobserver correlation was tested with calculation of the kappa coefficient. <h3>Results</h3> A poor interobserver correlation was found among pathologists (kappa – 0.19), and no airway sign or symptom was predictive of a positive GPA biopsy. Several pitfalls were noticed: lack of adequate clinical information on files (including endoscopic); incomplete relevant information sent to pathologists and inadequate tissue sampling, Nevertheless, in patients with generalised disease, a 2.6 probability to obtain a diagnostic GPA airway biopsy was found. After expert pathologist's review, and applying Devaney et al and Travis et al proposed criteria, from 16 initial GPA diagnoses, the number increased to 25. It further raised to 35/50 randomised biopsies when ANCA results were incorporated, and the EMA algorithm was applied. <h3>Conclusions</h3> Carefully retrieved clinical, endoscopic and serological data, coupled with systematic histopathologic sample review in patients with a GPA suspicion shall be incorporated in an orderly fashion in order to increase the diagnostic yield of this malady, especially in patients with the limited form of the disease. <h3>References</h3> [1] Devaney KO, Travis WD, Hoffman G, Leavitt R, Lebovics R, Fauci AS. Interpretation of head and neck biopsies in Wegener's granulomatosis. A pathologic study of 126 biopsies in 70 patients. Am J Surg Pathol1990;14:555–564. [2] Travis WD, Hoffman GS, Leavitt RY, Pass HI, Fauci AS. Surgical pathology of the lung in Wegener's granulomatosis. Am J Surg Pathol1991;15:315–333. [3] Watts R, Lane S, Hanslik T, Hauser T, Hellmich B, Koldingsnes W, et al. Development and validation of a consensus methodology for the classification of the ANCA-associated vasculitides and polyarteritis nodosa for epidemiological studies. Ann Rheum Dis2006;66:222–227. <h3>Acknowledgements</h3> None <h3>Disclosure of Interest</h3> None declared