Differential Diagnosis for Red Painful Elbows and Knees with Swelling

Single Most Likely Diagnosis

• Juvenile Idiopathic Arthritis (JIA): This condition is characterized by chronic joint inflammation and is the most common rheumatic disease in children, often presenting with symmetric joint involvement, including the elbows and knees, and can cause redness, pain, and swelling.

Other Likely Diagnoses

• Septic Arthritis: A bacterial infection within a joint, which can cause severe pain, redness, swelling, and warmth, typically affecting one joint at a time but can be multiple in certain cases.
• Reactive Arthritis: A form of arthritis that occurs as a reaction to an infection elsewhere in the body, often presenting with joint pain and swelling, especially in the knees and elbows, and can be accompanied by other symptoms like urethritis and conjunctivitis.
• Rheumatoid Arthritis (RA): An autoimmune disorder that causes chronic inflammation in the joints, leading to pain, swelling, and stiffness, often affecting the hands and feet but can also involve larger joints like the elbows and knees.

Do Not Miss Diagnoses

• Lyme Arthritis: Caused by the bacterium Borrelia burgdorferi, transmitted by tick bites, and can lead to intermittent or persistent arthritis, particularly in the knees, which can be painful and swollen.
• Gonococcal Arthritis: A complication of gonorrhea infection, which can cause septic arthritis, characterized by sudden onset of joint pain, swelling, and decreased range of motion, often affecting the knees, elbows, and wrists.
• Osteomyelitis: An infection of the bone, which can cause pain, redness, and swelling over the affected bone, and if near a joint, can mimic arthritis.

Rare Diagnoses

• Psoriatic Arthritis: A condition that occurs in some people with psoriasis, leading to joint pain, swelling, and stiffness, often affecting the knees and elbows, and can cause redness and swelling of the skin over the joints.
• Ankylosing Spondylitis: A type of arthritis that primarily affects the spine, but can also affect other joints, causing inflammation, pain, and stiffness, and in rare cases, can present with peripheral joint involvement like the elbows and knees.
• Sarcoid Arthritis: A condition where sarcoidosis, an inflammatory disease, affects the joints, causing pain, swelling, and stiffness, which can involve any joint but is less common in the elbows and knees.