Background IgG4-related disease is a rare entity consisting of inflamation and fibrosis that has been described in many locations. Diagnosis may be challenging and concrete diagnostic criteria have been established recently.
Objectives To describe the clinical presentation and histopathological characteristics of a series of patients diagnosed with IgG4-related disease (IgG4-RD) in Spain.
Methods A retrospective multicentric study was performed. Clinical data were obtained from institution medical records. A clinical protocol and a joint database were created to constitute the IgG4-related Disease Spanish Register. Patients were enrolled from 14 different centers. Pathologic studies were conducted according to Deshpande et al.  diagnostic criteria (Histologically highly suggestive or probable IgG4-RD). Patients with insufficient histopathological evidence of IgG4-RD were excluded.
Results Thirty-five patients were included in the study, 27 of whom (77.1%) were male. Median age at diagnosis was 55 years (IQR 29 years). Two patients (5.7%) had been diagnosed of Hashimoto's thyroiditis, one (2.9%) of rheumatoid arthritis and one (2.9%) of ANCA-negative associated vasculitis. Thirty-one (88.6%) patients had surgical biopsy specimens and 4 (11.4%) had fine needle aspiration samples. Eighteen (51.4%) patients were included in the histologically highly suggestive IgG4-RD and 17 (48.6%) in the probable IgG4-RD group. Median serum IgG4 for both groups was 241 mg/dL (IQR 1234.5 mg/dL) and 102 mg/dL (IQR 1082.9 mg/dL) (normal 5-145mg/dL). Regarding the immunohistochemical exams, the median IgG4 count at 400x and IgG4/IgG ratio were 60 cells/hpf (IQR 32.5 cells/hpf) and 0.48 (IQR 0.16) in the highly suggestive IgG4-RD group, and 29.2 cells/hpf (IQR 36.5 cells/hpf) and 0.22 (IQR 0.19) in the probable IgG4-RD group. All patients presented 2 or more typical pathologic findings, and the distribution was: lymphoplasmocitary infiltrate 31 (88.6%), storiform fibrosis 30 (85.7%) and obliterative phlebitis 12 (34.3%). Eighteen (51.4%) patients presented IgG4-RD with more than one organ affected at presentation. The global distribution by specific organic affection was: pancreas 7 (20%), lacrimal glands 4 (11.4%), orbitary pseudotumor 6 (17.1%), extraocular muscles 1 (2.9%), salival glands 4 (11.4%), pachimeninges 2 (5.7%), thyroides 1 (2.9%), aorta 4 (11.4%), mediastinum 1 (2.9%), retroperitoneum 13 (37.1%), mesenterium 3 (8.6%), lymph nodes 1 (2.9%), biliary ducts 1 (2.9%), gallbladder 2 (5.7%), lung 3 (8.7%), pleura 2 (5.7%), pericardium 1 (2.9%), kidney 2 (5.7%) and maxilar 8 (22.9%).
Conclusions IgG4 related disease is a rare entity in our country. The most usual presentation was in middle aged males and synchronic autoimmune diseases were scarce. The majority of patients presented a probable IgG4-RD, mainly because of low IgG4/IgG ratios. The most frequently affected organs were, as described in others series, retroperitoneum, maxilar, pancreas and orbitary pseudotumor. More collaborative studies are required in order to assess the real prevalence of the disease and the frequence of the different presentations.
Deshpande V, Zen Y, Chan JK, et al. Consensus statement on the pathology of IgG4-related disease. Mod Pathol. 2013;26(8):1150-1.
Disclosure of Interest None declared