Scleroderma renal crisis or thrombotic thrombocytopenic purpura: seeing through the masquerade.

SCLERODERMA: renal crisis (SRC), a somewhat rare but serious complication of systemic scleroderma, is one of only a few known rheumatologic emergencies; it presents in as many as 10% of patients with scleroderma. Before the use of angiotensin converting enzyme (ACE) inhibitors to treat SRC, the mortality rate for SRC was extremely high-as much as 90% after 1 year. However, the mortality rate has significantly improved with the early and aggressive use of ACE inhibitors. SRC typically includes acute renal failure and accelerated hypertension. Patients may report headache, changes in vision, fever, dyspnea, and encephalopathy. Laboratory study results can show elevated creatinine levels, thrombocytopenia, and microangiopathic hemolytic anemia (MAHA) with schistocytes on blood smear. Given this clinical and laboratory presentation, SRC can easily be mistaken for TTP in clinical practice, as we demonstrate in 2 presentations of similar cases of SRC, the first in a 36-year-old Caucasian woman and the second in a 54-year-old Caucasian woman. In both cases, SRC masqueraded as TTP, and both patients were almost mistakenly treated for TTP until the clinical picture changed and certain laboratory test and kidney biopsy results confirmed otherwise.