Which autoimmune disease is MOST commonly associated with Sjögren syndrome?

Correct answer: D. Rheumatoid arthritis

• A. SYSTEMIC LUPUS ERYTHEMATOSUS is the second most common association, but it is less frequent than rheumatoid arthritis.
• B. MULTIPLE SCLEROSIS is a demyelinating disease of the central nervous system and is NOT part of the Sjögren spectrum.
• C. SYSTEMIC SCLEROSIS can occur with Sjögren and adds its own oral problems — microstomia, widened PDL space and resorption — but it is a considerably less common association.
• D. CORRECT. RHEUMATOID ARTHRITIS is the most frequent connective-tissue disease accompanying SECONDARY Sjögren syndrome — more common than lupus, despite lupus often being the assumed answer. Roughly a fifth of RA patients develop secondary Sjögren. The distinction matters: PRIMARY Sjögren occurs alone, SECONDARY Sjögren occurs with another autoimmune disease, most often RA.

Note: Dental consequences of the xerostomia are severe and predictable: rampant CERVICAL and ROOT caries, candidiasis, difficulty wearing dentures, and a lifetime risk of MALT LYMPHOMA in the salivary glands around 5%. Any persistent unilateral parotid enlargement in a Sjögren patient needs investigation.