A rare case of systemic autoimmune disease with intricate features of systemic sclerosis, lupus, polymyositis and rheumatoid arthritis. Overlap syndrome or mixed connective tissue disease?

We report an unusual case of connective tissue disease characterized by the coexistence of signs, symptoms and immunological features of 4 defined autoimmune diseases: systemic lupus erythematosus (SLE), systemic sclerosis (SSc), polymyositis (PM) and rheumatoid arthritis (RA). A 53-year-old female was admitted in our clinic with massive polyserositis (pretamponade) as well as skin, joint, muscular lesions and altered general status. The problem we found was the difficulty of including this case in a known clinical entity; SSc/SLE/PM//RA overlap syndrome and mixed connective tissue disease were the two most plausible diagnoses. We discuss the particularities of these clinical and immunological associations and the appropriate therapeutic options used in this kind of patients.