Differential Diagnosis for Rash on Face, Positive ANA, Rapid Heart Rate, and Dizziness

Single Most Likely Diagnosis

• Systemic Lupus Erythematosus (SLE): This diagnosis is likely due to the combination of a rash on the face (possibly a butterfly rash), a positive antinuclear antibody (ANA) test, and systemic symptoms such as rapid heart rate and dizziness. SLE is a chronic autoimmune disease that can affect various parts of the body, including the skin, joints, kidneys, brain, and other organs.

Other Likely Diagnoses

• Rheumatoid Arthritis: Although less likely than SLE given the specific combination of symptoms, rheumatoid arthritis can present with a rash, positive ANA (though less common), and systemic symptoms including rapid heart rate and dizziness due to inflammation and potential cardiac involvement.
• Sjögren's Syndrome: This autoimmune disorder can cause skin rashes, positive ANA, and systemic symptoms. However, it is more commonly associated with dry eyes and mouth.
• Mixed Connective Tissue Disease: This disease combines features of lupus, scleroderma, and rheumatoid arthritis, and can present with a variety of symptoms including rash, positive ANA, and systemic symptoms.

Do Not Miss Diagnoses

• Severe Infection (e.g., Endocarditis, Sepsis): Infections can cause rash, rapid heart rate, and dizziness. A positive ANA can sometimes be seen in chronic infections. Missing a severe infection could be fatal.
• Thyroid Storm: This is a life-threatening complication of untreated or undertreated hyperthyroidism. Symptoms can include rash, rapid heart rate, and dizziness. Although ANA is not typically positive, thyroid antibodies might be.
• Drug Reaction (e.g., DRESS Syndrome): Drug reactions can cause rash, fever, and systemic symptoms including rapid heart rate and dizziness. Some drug reactions can also induce positive ANA.

Rare Diagnoses

• Sarcoidosis: This condition can cause skin rashes, systemic symptoms, and occasionally a positive ANA. It is characterized by the growth of granulomas in various parts of the body.
• Relapsing Polychondritis: A rare autoimmune disorder that can cause a variety of symptoms including skin rash, and systemic symptoms. It is characterized by recurring episodes of cartilage inflammation.
• Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. Some types can cause skin hyperextensibility and easy bruising, which might be mistaken for a rash, along with systemic symptoms due to vascular or cardiac involvement.