Differential Diagnosis for Rash with Joint Swelling
Single Most Likely Diagnosis
- Rheumatoid Arthritis (RA): This is a common autoimmune disorder that often presents with joint swelling and can be associated with various skin manifestations, including rashes. The combination of joint symptoms and rash makes RA a leading consideration.
Other Likely Diagnoses
- Lupus: Systemic lupus erythematosus (SLE) is another autoimmune disease that can cause both joint swelling and a variety of skin rashes, making it a plausible diagnosis.
- Psoriatic Arthritis: This condition combines the swollen, scaly skin of psoriasis with joint pain and arthritis, fitting the described symptoms.
- Reactive Arthritis: Previously known as Reiter's syndrome, this form of arthritis occurs as a reaction to an infection elsewhere in the body and can cause joint swelling along with skin lesions.
Do Not Miss Diagnoses
- Lyme Disease: Caused by a tick-borne bacterium, Lyme disease can lead to joint swelling and a characteristic "bull's-eye" rash. Missing this diagnosis could lead to serious complications if not treated promptly.
- Gonococcal Arthritis: A condition caused by a gonorrhea infection that has spread to the joints, leading to swelling and potentially a rash. It's crucial to consider this due to its implications for sexual health and the potential for severe outcomes if untreated.
- Septic Arthritis: Although not typically associated with a rash, in some cases, an infectious process causing septic arthritis could also lead to a rash, especially if the infection is systemic. This is a medical emergency requiring immediate attention.
Rare Diagnoses
- Relapsing Polychondritis: A rare autoimmune disorder that can cause inflammation of the cartilage in various parts of the body, leading to joint swelling and potentially skin manifestations.
- Sarcoidosis: A condition characterized by the growth of granulomas (inflammatory cells) in different parts of the body, which can lead to joint swelling and skin rashes, among other symptoms.
- Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues, potentially leading to joint hypermobility and skin manifestations.