A patient suffering from symmetrical and persistent painless swelling of lacrimal and salivary gland with no or less xerostomia, responds to steroid therapy. What could be the possible diagnosis for this patient?

IgG4-related disease (Mikulicz disease ) often requires immediate, aggressive treatment with systemic corticosteroids to prevent significant organ damage and failure. Glucocorticoid-sparing agents, such as azathioprine, mycophenolate mofetil, and methotrexate, also can be used. Most patients show a rapid response to immunosuppressive therapy and have a favorable prognosis. For patients with recurrent disease, B-cell depletion with rituximab can be effective.      The treatment of the patient with Sjögren syndrome is mostly supportive. The dry eyes are best managed by periodic use of artificial tears. Artificial salivas are available for the treatment of xerostomia; sugarless candy or gum can help to keep the mouth moist. Symptoms often can be relieved by the use of oral hygiene products that contain lactoperoxidase, lysozyme, and lactoferrin. Ref: ORAL AND MAXILLOFACIAL PATHOLOGY, Neville, FOURTH EDITION  page no 434,437