Systemic Lupus Erythematosus

SYSTEMIC LUPUS ERYTHEMATOSUS 46A

A 22-year-old African American woman reports intermittent joint pain in her right knee and the joints of the fingers of her right hand, especially the proximal interphalangeal (PIP) joints, as well as a rash on her cheeks and nose that appears after sun exposure. On review of systems, she reports chest pain with deep breaths. On physical examination, she has painless oral ulcers on her palate; a pleural friction rub; and a facial rash, sparing the nasolabial folds. Her urine dipstick reveals 3+ protein, and laboratory testing reveals a white blood cell count of 3400/mcL, a platelet count of 89,000/mcL, a positive rapid plasma reagin (RPR) test result, a positive antinuclear antibody (ANA) test result with a titer of 1:320, and a positive anti-Smith antibody test result.

What are the salient features of this patient’s problem? How do you think through her problem?

Salient features: Young African American woman; symmetric, intermittent arthritis involving the fingers and knee; malar rash that spares the nasolabial folds; photosensitivity; signs and symptoms of pleuritis (chest pain, friction rub); oral ulcers; renal involvement (proteinuria); leukopenia and thrombocytopenia; false-positive syphilis test result; positive ANA result with high titer; positive anti-Smith test result

How to think through: Which populations are most affected by lupus? What are the typical timing and pattern of progression in lupus? What features of lupus are found on history? (Recall the common symptoms by building a mental image of the affected areas of the body—cognition, conjunctivitis or vision change, hair loss, sicca symptoms, oral ulcers, malar rash, photosensitivity, pleuritis, pericarditis, gastrointestinal symptoms, joint pain, Raynaud phenomenon). How might you assess involvement of the kidneys? (Urinalysis, renal biopsy.) What are the important serologies for lupus? (ANA is 99% positive but is nonspecific; anti-Smith and anti–double-stranded DNA have low sensitivity but high specificity.) How is the complete blood count useful? Will complement levels be elevated or decreased? What features of rheumatoid arthritis (RA) and lupus overlap? (Arthritis, pleural inflammation, leukopenia.) How can you differentiate RA from lupus? (The arthritis in RA more often affects the small joints of the hands and feet; is symmetrical; and shows evidence of inflammation on examination—rubor [redness], dolor [pain], calor [warmth], tumor [swelling]—and erosions on radiographs).