MM is a hematologic malignancy characterized by the proliferation of a clone of plasma cells that ultimately causes organ damage and the production of abnormal proteins. Sjögren's syndrome rarely coexisted with MM, a chronic autoimmune disease affecting exocrine glands and presenting very unique diagnostic and management challenges to the physician. This case illustrates the therapeutic journey of a patient with coexisting MM and Sjögren's syndrome and points out the importance of care provided in a multidisciplinary fashion.

A 64-year-old female patient with a history of hypertension for 14 years and prostheses of both hips was referred to the rheumatology department with dry eyes and joint pains. The presence of anti-SSA antibodies and diminished results of the Schirmer test supported the diagnosis of Sjögren's syndrome; thus, hydroxychloroquine and prescription of artificial tears were started. Symptomatic treatment was begun because the development of albumin and total protein inversion suggested plasma cell dyscrasia.

Further work-up for immunofixation electrophoresis and bone marrow biopsy confirmed IgG lambda-positive MM. She was subsequently treated with VRD (bortezomib, lenalidomide, and dexamethasone), followed by an autologous BMT in May 2024. Post-transplant maintenance was given with lenalidomide. She also developed sensory neuropathy, which was managed with pregabalin, with no recurrence of MM on follow-up.

The case epitomizes the complex diagnostic interplay between MM and Sjögren's syndrome. Symptoms of fatigue and protein abnormalities can easily be attributed to an autoimmune condition, with a delayed diagnosis of MM. Multidisciplinary collaboration has been critical for management of comorbidities and assurance of timely diagnosis. The patient responded well to BMT and maintenance therapy, proving personalized care. Furthermore, long-term treatment shows the necessity of monitoring drug-induced neuropathy. This case report adds to the growing awareness of rare concomitant autoimmune disorders and hematologic malignancies, with a reminder for vigilance in complex presentations and the delivery of adaptive multidisciplinary care.