AB1060 A RARE IgG4-REALTED DISEASE PHENOTYPE WITH BONE DESTRUCTIVE LESIONS
Authors: E. Sokol, S. Palshina
Journal: Annals of the Rheumatic Diseases (2020)

Background: IgG4-related disease (IgG4-RD) is an immunomediated fibroinflammatory condition with systemic course that can affect almost any organ in the body. In the majority of cases it is a benign condition with slow progression. The clinical symptoms are usually determined by compression of nearby anatomic structures by tumefective lesions, but not by invasive growth of the pseudotumor with the destruction of the organs. Bone destruction always raises suspicion of malignant tumor, but it should be considered in the course of IgG4-RD as well. Objectives: To report a very rare bone destructive phenotype of IgG4-RD. Methods: We report 5 cases of biopsy proven IgG4-RD with bone destructive lesions. Results: In our cohort of patients there were 3 patients with multiple fascial bones destruction due to maxillary sinus pseudotumor expansion and 2 patient with vertebral destruction lesions. Patients 1, 2 and 3 with facial bone destruction were young men aged 42, 36 and 28 years. In all cases the primary lesion was located in the maxillary sinus with expansion to the fascial soft tissues and orbit. Two patients had probable and 1 possible IgG4-RD diagnosis according to consensus diagnostic criteria, 2011. All patients were treated with rituximab and low doses of glucocorticoids with improvement of clinical symptoms (fascial edema, eye pain and/or headache), but lacking in radiologic improvement. Patient 4 is a 51-year-old man who developed retrosternal pain, mimicking angina pectoris. Chest CT showed a tumor of posterior mediastinum, infiltrating the right lung and Th6-Th8 bodies destruction. Biopsy of the lesion revealed lymphoplasmatic infiltrate with lymph follicles formation, few eosinophils, significant diffuse fibrosis. Immunohistochemical study, showed IgG:IgG4 ratio &gt;40%. The serum IgG4 concentration was 1.94 g/l (normal range below 2.0 g/l). Combined treatment was administered: rituximab 500 mg weekly #4 and cyclophosphamide 1000 mg + methylprednisolone 250 mg IV every 2 weeks #6. After that - cyclophosphamide 200 mg per week intramuscularly, methylprednisolone 4 mg daily per os. Due to spinal instability the patient undergone surgery. Six months later at check-up examination CT has shown a dramatic decrease of the mediastinal infiltrate. The treatment with cyclophosphamide and oral metylprednisolone was tapered gradually during 2 years due to no sites of pathological hypermetabolic activity were found on PET. Patient 5 is a 60-year-old woman who had spinal surgery for C2 odontoid destruction. Biopsy revealed chronic inflammatory with massive fibrosis. 1,5 years later she developed salivary glands enlargement. During evaluation she had elevated serum IgG4 4.9 g/l and IgM 4.1 g/l (normal range below 0.6-3.7 g/l), serum protein electrophoresis with immunofixation showed monoclonal IgMĸ 3.2 g/l. Left submandibular salivary gland biopsy revealed significant fibrosis, dense lymphoplasmatic infiltrate forming lymph follicle with IgG:IgG4 ratio 50-80% and no pathological signs of lymphoma. The patient was treated with rituximab 500 mg per week #2 and cyclophosphamide 1000 mg + methylprednisolone 250 mg IV every 2 weeks #3. The treatment was discontinued because of toxic hepatitis. Unfortunately, no follow-up was available. The tissue specimens after spinal surgery were also unavailable. Conclusion: IgG4-RD can manifest by bone, including vertebral, destructive lesions and thus should be included when considering differential diagnosis in patients with bone destruction. Disclosure of Interests: None declared