The most common connective tissue disease is Systemic lupus erythematosus (SLE) due to its high prevalence and multisystem involvement. SLE is characterized by autoimmune-mediated inflammation affecting skin, joints, kidneys, and other organs. It presents with diverse clinical features such as malar rash, arthritis, and renal involvement, making it a common diagnosis among connective tissue diseases. Unlike scleroderma, polymyositis, and dermatomyositis, SLE has a broader spectrum and affects a larger population globally. Thus, recognizing SLE is crucial for timely diagnosis and management.

Reference: Harrison’s Principles of Internal Medicine, Fauci et al., 20th Edition.