”Doctor, I have joint pain, do I have rheumatism?” “Do I have rheumatism or rheumatoid arthritis?” “They say rheumatoid arthritis affects the heart, will my heart break? This is the most common question asked by rheumatologists. Rheumatism, rheumatoid, gout, and arthritis …… are like a tangled mess of twine. The rheumatologists who face these questions every day can only silently look up at the sky except for the thousand and one explanations. What are the rheumatic diseases? The rheumatology specialty is called rheumatic diseases, which refers to a group of diseases affecting bones, joints and their surrounding soft tissues such as muscles, tendons, bursae, fascia and nerves. The most commonly mentioned category is diffuse connective tissue disease (CTD), which is a non-organ-specific autoimmune disease. Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are members of the CTD group, while ankylosing spondylitis (AS) belongs to the category of spondyloarthropathies. Osteoarthritis (OA), a common disease in the elderly, is a representative of degenerative changes; gout and pseudogout are both metabolic and endocrine related; rheumatic fever is an infection-related rheumatic disease. The “butterfly” and “moth” are not a family, rheumatoid arthritis, ankylosing spondylitis, osteoarthritis, rheumatic fever, gout, although they all have arthritic performance, but the root is not the same thing at all. What is rheumatic fever? Rheumatic fever (RF) is an acute or chronic systemic inflammatory disease of connective tissue that recurs after infection with group A group B hemolytic streptococcus in the throat. The 5 major manifestations are: wandering polyarthritis (more common in large joints), cardiac inflammation, subcutaneous nodules, erythema annulare, and chorea. These manifestations can occur separately or in combination and have many subtypes. During the long years of lack of antibiotic treatment, the consequences of infection were unpredictable. A small sore throat and tonsillitis followed by what could be rheumatic fever and heart valve disease. The arthritis of rheumatic fever does not leave joint deformities and is not terrible, but heart valve disease severely impairs the patient’s ability to work and life expectancy. By the middle of the 20th century, with the widespread use of antibiotics, the incidence of rheumatic fever declined significantly in countries around the world. In the 1980s, rheumatic fever was also rare in China. However, in the past 20 years, the incidence of rheumatic fever has rebounded and its epidemiological pattern is changing. For this disease, the etiologic treatment of removing streptococcal foci of infection is the most important, and benzathine penicillin is now recognized as the drug of choice. What is rheumatoid arthritis? Rheumatoid arthritis (RA) is a connective tissue disease of unknown etiology characterized by chronic, symmetric, aggressive small arthritis, often associated with extra-articular organ involvement and positive serum rheumatoid factor (RF) and CCP antibodies. The most important pathological mechanism of RA is the formation of subchondral opacities in the inflammatory state and their erosive destruction of cartilage and bone. The most common clinical manifestations of RA are morning stiffness, swelling and pain in the wrist, metacarpophalangeal and proximal interphalangeal joints, and joint destruction and deformity. The pathology of RA is mainly composed of synovial lining cell proliferation, massive interstitial inflammatory cell infiltration, microvascular neovascularization, formation of vascular opacities and destruction of cartilage and bone tissue. At this point, I think we all understand why “rheumatic fever” and “rheumatoid arthritis” are so easily confused. Rheumatoid arthritis, an informal term derived from rheumatic fever, has left a deep imprint on people’s memory for thousands of years with the power of rheumatic heart disease, so much so that it is still occupying a place in the name of the disease thirty years after it has gradually withdrawn from our attention. Not to mention the confusion caused by the fact that the abbreviation RF is identical to the abbreviation for rheumatoid factor (RF), the hallmark of RA. Perhaps, with the passage of time, this confusion will eventually be forgotten.