IgG4-related Disease, Retrospective Histopathological Diagnosis. Prevalence in an University Hospital

IntroductionIgG4 related diseases (IgG4-RD) are characterized mainly by organic dysfunction and inflammation with lymphoplasmacytic cells infiltration.MethodsWe conducted a retrospective study. We analyzed patients with a diagnosis of IgG4-RD through histopathologic registries. We divided the study into three phases: (i) extraction of data from the registries of the Pathology Department, including specimens reported with: non-specific inflammation with plasmatic cell infiltration, inflammatory pseudo-tumors and storiform fibrosis, and excluding any report of cancer or infection; (ii) from the selected specimens, three pathologists microscopically re-analyzed these biopsies and included only those who had at least two of the inclusion criteria cited above; (iii) finally, immunostaining was performed in the specimens selected in the second phase. The selected biopsies were cataloged as compatible for IgG4-RD if they had at least 3 inclusion criteria and as probable if they had 2 inclusion criteria.ResultsOn the first phase of the study we analyzed 23,720 biopsies, from which we included 71 and excluded 29 specimens; the rest of the specimens (n=41) underwent immunostaining. From the biopsies included, 41.4% (n=17/71) were positive to IgG4, with the most common histological diagnosis for the positive specimens being granulomatous mastitis, which represented 12.1% of the specimens cataloged initially as probable. The rest of the positive biopsies were from aortitis, dacrioadenitis and/or sialoadenitis, lung pseudo-inflammatory tumor, pericarditis and chronic pancreatitis.ConclusionsThe suspicion of IgG4 related disease should not be based solely on clinical manifestations or serology. In the present study we confirm the characteristic changes of IgG4-RD in patients without initial clinical suspicion.

ResumenIntroducciónLas enfermedades relacionadas con IgG4 (ER-IgG4) se caracterizan por inflamación y disfunción orgánica asociadas a células plasmáticas productoras de IgG4.MétodosAnalizamos pacientes con ER-IgG4 de acuerdo con: a) búsqueda de resultados en la base de datos de Patología con: reacción inflamatoria inespecífica con infiltrado linfoplasmocítico, pseudotumores inflamatorios y fibrosis estoriforme; b) análisis microscópico de biopsias con criterios de inclusión de la primer fase, y c) inmunohistoquímica de biopsias seleccionadas en la segunda fase.ResultadosEvaluamos en la primera fase 23.720 biopsias, y a 41/71 que reunieron los criterios de inclusión les realizamos inmunohistoquímica para IgG4. El 41,4% de estas tuvieron IgG4+, y el diagnóstico histológico más frecuente asociado fue mastitis granulomatosa (12,1% de muestras catalogadas inicialmente como probables). El resto incluyeron reportes de aortitis, dacrioadenitis o sialoadenitis, pseudotumor inflamatorio pulmonar y pancreatitis crónica.ConclusionesLa sospecha de enfermedades relacionadas con IgG4 no debe basarse únicamente en manifestaciones clínicas distintivas o solo en serología. Nuestro estudio incluye pacientes con ER-IgG4 sin sospecha clínica inicial.