Case #008

A malar rash that spares the nasolabial folds is the detail worth pausing on, because that sparing is what separates it from rosacea and seborrhoeic dermatitis, both of which favour exactly the folds lupus leaves alone. Add photosensitivity, inflammatory arthritis, oral ulcers and cytopenias in a young woman and the pattern is systemic lupus. One laboratory oddity supports it further: an ESR of 58 against a CRP of 6 is the classic dissociation of a lupus flare, and a CRP that climbs instead should raise the question of infection rather than disease activity. The antibodies then sort sensitivity from specificity. ANA is positive in almost every patient with lupus and in plenty of people without it, so it rules out rather than rules in; anti-dsDNA and anti-Smith are the specific ones, and anti-dsDNA titres tend to track activity, particularly in the kidney. Low C3 and C4 say complement is being consumed by immune complexes right now. Proteinuria with red cell casts is what makes this urgent rather than merely uncomfortable, since casts mean glomerular inflammation, and it is why a biopsy is planned: the class of nephritis dictates the drug. Hydroxychloroquine is given to essentially everyone regardless of severity, because it lowers flares, organ damage and mortality over years. Corticosteroids cover the flare itself at a dose matched to severity and are tapered as fast as tolerated, since the long-term harm is cumulative. Azathioprine, mycophenolate or belimumab spare steroids in organ-threatening disease, with cyclophosphamide or rituximab held back for severe nephritis or cerebral involvement.