AB1165 Monoclonal gammopathy in rheumatic diseases and its role in predicting malignant transormation
Authors: Y. Yang, Y. Liu, L. Chen, Y. Jia, Z. Li
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> The monoclonal gammopathy (MG) constitutes a group of diseases characterised by the proliferation of a single clone of plasma cells or B-lymphocytes. The spectrum of conditions capable of producing MG mainly includes a premalignant state known as monoclonal gammopathy of undetermined significance (MGUS) and a group of malignant hematologic disorders. In previous studies, significantly increased risk of MG was seen in patients with a history of various rheumatic diseases. We analysed 41 hospitalised patients with underlying rheumatic diseases who were diagnosed with MG at out institute from 2010 to 2017, in order to identify clinical clues for early diagnosis, as well as the risk factors for MG and malignant hematologic neoplasias in patients with rheumatic diseases. <h3>Objectives</h3> To analyse the clinical spectrum, laboratory characteristics and outcomes of monoclonal gammopathy (MG) in patients with rheumatic diseases. <h3>Methods</h3> Screening for the presence of MG was performed in 872 inpatients with rheumatic diseases from January 2010 to July 2017. A total of 41 patients were enrolled. Their clinical and biological features in addition to outcomes were described. For each patient with primary Sjögren syndrome (pSS), 2 age- and sex-matched pSS patients without MG were selected as controls. Risk factors for the presence of MG and malignant haematological neoplasias were assessed. <h3>Results</h3> MG was observed in patients with various rheumatic diseases, with SS the most frequent type. Serum M protein was detected in 37 patients. M components were observed in urine in the other 4 patients. High ESR, albumin/globulin inversion, rheumatoid factor positicity, hypergammaglobulinemia, hypocomplementemia were common features, presented in more than half of the 41 patients. Patients with pSS, when complicated with MG, showed a higher rate of abnormal urine NAG (71.4% vs 15.8%, p=0.025), higher levels of ESR [55.0 (53.5) mm/h vs 21.0 (31.8) mm/h, p=0.001], ESSDAI [26.0 (25.0) vs 12.0 (9.0), p=0.006] and ClinESSDAI scores [24.0 (25.0) vs 10.5 (10.0), p=0.011]. Multivariate analysis revealed that the disease activity, assessed by either ESSDAI [adjusted OR 1.127 (95%CI 1.015–1.251), p=0.025] or ClinESSDAI [adjusted OR 1.121 (95%CI 1.011–1.242), p=0.030], was the only independent risk factor for the presence of MG. During the follow-up, 2 patients had transient serum M protein, 2 had isotype switch, 1 progressed to multiple myeloma (MM) and another 2 experienced renal injuries attributed by monoclonal or polyclonal plasma cell interstitial infiltration. Seven (17.1%) of the 41 MG patients presented haematological neoplasias, 4 with MM, 2 with smouldering multiple myeloma and 1 with B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type. The presence of light-chain MG was associated with the development of MM [OR 17.5 (95%CI 1.551–197.435), p=0.041], but not with an increased risk of lymphoma or SMM. <h3>Conclusions</h3> MG was observed in patients with various rheumatic disorders, with SS being the most common type. The presence of MG might associated with higher disease activity. The development of haematological neoplasias including MM and lymphoma was seen in this setting. Therefore, we recommend the screening for MG and close monitoring for potential malignant transformation in patients with rheumatic diseases as needed. <h3>Disclosure of Interest</h3> None declared