relapsing polychondritis vs. lupus

I don't quite understand the differences in relapsing polychondritis and lupus. Can anyone give me a summary of how they differ? Thanks in advance. -Matthew

[Dr. Kokil Mathur]

Hi!
Relapsing polychondritis is thought too be an autoimmune disease as its cause is not known. This disease is characterized by destruction of cartilage, especially in nose, ear, throat, joints and rib cage, and heart valves, but can affect cartilage in any organ. The symptoms vary with the organ affected. However, fever and rash may be present in all cases and has a relapsing presentation. Other than that it can cause sudden loss of hearing or blurred vision, or difficulty in breathing, swallowing, or cause signs of dementia and seizures etc if brain is involved.
Lupus is also an autoimmune disease that affects skin, joints, kidneys, and other organs. Signs and symptoms may be same as that of relapsing polychondritis, except that in systemic lupus the malar rash is on nose bridge and cheek bones. In discoid lupus, the rash is very characteristic, circular, with scarring. The American College of Rheumatology (ACR) has identified 11 characteristics that should be present for diagnosis of SLE or lupus and it is important that at least 4 of the characteristics should be present for a confirmed diagnosis. This includes serositis (pleurisy or pericardiatis, since you had bronchial infection, ask your doctor to check for pleurisy or inflammation of lining of lung), mouth ulcer, low WBC or leucopenia/anemia (hemolytic)/thrombocytopenia/lymphopenia, arthritis, kidney involvement, high ANA, finding of Smith Antibody (Anti-Smith)/ dsDNA/ antiphospholipid antibodies (anticardiolipin immunoglobulin G [IgG] or immunoglobulin M [IgM] or lupus anticoagulant), neurological features like seizures and psychosis, discoid rash and malar rash.
The two conditions can be differentiated on the basis of tests. While there is no test specific for relapsing polychondritis, antinuclear antibody (ANA) panel is very specific for lupus. Hope this helps. Take care!