Differential Diagnosis for Fever with Synovitis of Joints

Single Most Likely Diagnosis

• Rheumatoid Arthritis (RA): This is a common autoimmune disorder that often presents with fever, joint pain, and swelling, particularly in the hands and feet. The presence of synovitis, which is inflammation of the synovial membranes surrounding the joints, is a hallmark of RA.

Other Likely Diagnoses

• Lyme Disease: Caused by the bacterium Borrelia burgdorferi, transmitted through tick bites. It can lead to fever, joint pain, and swelling, especially in the knees. The disease often presents in stages, with the initial stage characterized by a distinctive rash, followed by neurological and joint manifestations.
• Gonococcal Arthritis: A type of septic arthritis caused by Neisseria gonorrhoeae, which can lead to fever, joint pain, and swelling, particularly in young, sexually active individuals.
• Reactive Arthritis: Previously known as Reiter's syndrome, this form of arthritis occurs as a reaction to an infection elsewhere in the body, often in the gastrointestinal tract or the urethra. It is characterized by the classic triad of arthritis, urethritis, and conjunctivitis, along with fever.

Do Not Miss Diagnoses

• Septic Arthritis: An infection within a joint, which can be caused by bacteria, viruses, or fungi. It is a medical emergency requiring prompt diagnosis and treatment to prevent joint destruction and systemic complications. Fever and joint pain are key symptoms.
• Lupus: Systemic Lupus Erythematosus (SLE) is an autoimmune disease that can affect multiple systems, including the joints, skin, kidneys, and brain. Joint pain and swelling, along with fever, are common manifestations.
• Osteomyelitis: An infection of the bone, which can spread to the adjacent joint, causing fever and joint pain.

Rare Diagnoses

• Whipple's Disease: A rare, systemic bacterial infection caused by Tropheryma whipplei, which can lead to fever, joint pain, and malabsorption.
• Relapsing Polychondritis: A rare autoimmune disorder characterized by recurring episodes of cartilage inflammation, which can affect the ears, nose, trachea, and joints, leading to fever and joint pain.
• Sarcoidosis: An inflammatory disease that can affect multiple parts of the body, including the lungs, skin, and joints. It can cause fever, joint pain, and swelling, although joint involvement is less common than other manifestations.