In systemic autoimmune conditions, the arthritis can be in multiple joints, the way it is in rheumatoid arthritis, but it usually does not cause erosion or deformities. (Although this can occur sometimes, and when it does, the clinical picture can resemble that of RA.) In someone with SLE, erosive arthritis can be predicted by the development of a positive ACPA test. However, conventional therapy still focuses on treating the lupus even though you might develop arthritis. Having this overlap of positive tests for two autoimmune diseases is common, and when I see a lupus sufferer with joint involvement, it just reinforces my resolve to repair the gut bacteria because I know that there is an issue that is amplifying the SLE symptoms. Of course, everyone with autoimmune disease needs to repair his or her gut, but once there is knee arthritis, that should become the focus.
Sjögren’s syndrome (SS) affects exocrine glands throughout the body: organs that secrete fluids, such as the salivary glands in your mouth and the tear-producing lacrimal glands. Dysfunction in these particular glands causes dry mouth and dry eyes, respectively, but Sjögren’s sufferers may also experience vaginal dryness and reduced lubrication in the skin and respiratory tract. About 50 percent of people with primary SS have joint involvement, including the synovitis and bone erosion that is seen commonly in rheumatoid arthritis. In fact, patients often start out with Sjögren’s, progress to testing positive for rheumatoid factor or the anti-citrullinated peptide antibody, and end up with RA.
Scleroderma refers to thickened, hardened skin. When it involves internal organs, it is called systemic sclerosis. This is an autoimmune disease where not only is the skin affected, but also patients complain of fatigue, swollen hands, and muscle and joint pain. However, the joints usually do not exhibit swelling, and X-rays do not typically show synovitis or bone erosion. In the rare instances when inflammatory arthritis does arise, it often follows a pattern similar to that in RA, called an “overlap syndrome.” This is where it seems like you have both conditions going on at the same time. Scleroderma is diagnosed by blood tests, specifically anti-Scl-70, anti-centromere antibody (ACA), and anti-RNA polymerase III antibody. If any of these come back positive, it is likely that this is the underlying condition.
Dermatomyositis and polymyositis are inflammatory conditions affecting the muscles, and their primary symptoms are muscle weakness and pain, with the joints rarely involved. When the skin is affected, the diagnosis is dermatomyositis. Because they are part of the grouping of systemic rheumatic diseases, I am including them here just for your information. Finally, mixed connective tissue disease (MCTD) is a diagnosis given to people who have overlapping symptoms of lupus, systemic sclerosis, and polymyositis.