Killing Two Birds With One Stone: Successful Management With Rituximab in the Coexistence of Myasthenia Gravis and Marginal Zone Lymphoma.

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder characterized by motor weakness affecting various muscle groups. The simultaneous or sequential occurrence of lymphoma and MG, often seen in patients, could be influenced by common genetic and biological factors that drive unregulated lymphocyte growth, leading to autoimmunity and lymphoma. This case report describes a 72-year-old male with coexisting marginal zone lymphoma and MG, who exhibited a positive response to rituximab treatment intended for the lymphoma, but surprisingly effective for both conditions. The patient experienced significant improvement in MG symptoms and a decline in serum anti-acetylcholine receptor (AChR) antibodies, along with achieving hematologic remission in the lymphoma. These observations emphasize the potential therapeutic advantages of rituximab in treating cases with concurrent MG and lymphoma, providing useful insights for future research and multifaceted clinical management.