Primary Sjogren's Disease Coexisting With Myasthenia Gravis: Two Distinct Autoimmune Diseases Successfully Treated With a Rituximab-Based Induction Regimen.

Primary Sjögren's syndrome (pSS) and myasthenia gravis (MG) are autoimmune diseases and are rarely reported in coexistence. MG is a chronic autoimmune neuromuscular disease where antibodies bind to acetylcholine receptors or to functionally related molecules in the postsynaptic membrane, weakening the skeletal muscles and causing diplopia, ptosis, and difficulty in breathing and swallowing. In this report, we discuss the case of a 43-year-old female patient who presented with dry eyes, weight loss, fatigue, ptosis, dysarthria, and quadriparesis, which ultimately led to the diagnosis of pSS and MG. Severe dry eyes, myasthenic symptoms, hypokalemic paralysis, and pancytopenia were among the disease and treatment-related consequences that had to be managed during the course of treatment. The symptoms of MG and pSS were initially managed with high-dose corticosteroids, azathioprine, and pyridostigmine/neostigmine. Escalation to an induction regimen based on rituximab was required due to persistent disease activity of both MG and pSS. Significant hematological and clinical improvements were noted after treatment, highlighting rituximab's effectiveness in inducing remission in these overlapping autoimmune diseases. To the best of our knowledge, this is the first case in the literature where these coexisting diseases were simultaneously, successfully treated with a rituximab-based induction regimen.