Background Immunoglobulin G4-related systemic disease (IgG4-RSD) is a rapidlyemerging disease characterized by a diffuse or mass forming inflammatory reaction rich in IgG4-positive plasma cells associated with fibrosclerosis and obliterative phlebitis(1). As the number of diseases associated with IgG4-RSD continues to grow, the number of referral for suspected disease increases rapidly.
Objectives To evaluate the number of referral for suspected IgG4-RSD in two regional hospitals in Hong Kong in 2011 and to review the treatment experience.
Methods All patients referred for suspected IgG4-RSD in 2011 were identified through the clinical management system. Patient characteristics and treatment experiences were reviewed.
Results 8 patients were referred to the Rheumatology Specialist Clinic (RSC) for suspectedIgG4-RSD in 2011. 7 patients (90%) presented with diffuse or focal enlargement in one or more organs while one patient presented with Central Retinal Vein Occlusion(CRVO), raised inflammatory markers and patchy lung consolidative changes. Two of the patients were finally diagnosed to have autoimmune parotitis and Sjögren’s syndrome while another two still did not have their IgG4 level results at the time of study. For the patient with patchy lung consolidative changes, IgG-4 level was raised to 340 mg/dl (0-291 mg/dl) but the patient refused to have tissue biopsy. One patient was referred from the eye team for idiopathic orbital inflammation with abnormal soft tissue within both orbits encroaching onto the optic nerves and hypertrophied lateral rectus muscle. IgG-4 level was raised to 780 mg/dl and incisional biopsy of right subconjunctival soft tissue showed vasculitis with transmural inflammatory infiltrate rich in eosinophils. The patient was subsequently treated as IgG4-RSD with steroid and methotrexate with fair response.
Two patients were referred to the RSC in 2011 for diffuse enlargement of larcrimal, parotid and submandibular gland swelling. One of these patients was referred immediately soon after he presented while the other was referred only 7 years after he first presented. Their IgG4 levels were 1250 mg/dl and 1810 mg/dl respectively. In both cases, the diagnosis of IgG4-RSD was confirmed by lacrimal gland biopsy, showing reactive lymphoid hyperplasia and a ratio of IgG4/IgG-positive cells of more than 40%. Response to steroid treatment was satisfactory but in the former case, symptoms recur when prednisolone was tailed down to 10mg daily and azathioprine was introduced as steroid sparing agent with good effect.
Conclusions In conclusion, as the diagnostic criteria for IgG4 related disease developed more referral to the RSC is noted. Understanding the conditions that are associated with IgG4-RSD, e.g. idiopathic orbital inflammation, orbital myositis and lung involvement by IgG4-RSD(2-3), is critical for diagnosing and thus provide prompt treatment to patients.
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Disclosure of Interest None Declared