Taken Out of Context

A CLINICAL PROBLEM-SOLVING article by Michael Thomas from University of Michigan in Ann Arbor.
A 25-year-old woman with a history of depression, mitral-valve prolapse, and migraine presented with a 3-day history of fever, arthralgia, and severe generalized headache that was not characteristic of her previous migraines. On examination, the patient was afebrile , with a pulse rate of 120 beats per minute and a blood pressure of 98/41 mm Hg. She was somnolent but easily arousable. The neurologic examination was normal. Laboratory study showed a normocytic anemia and severe thrombocytopenia. A peripheral-blood smear revealed few platelets and some schistocytes. Thrombotic thrombocytopenic purpura was suspected. Plasma exchange and corticosteroid therapy were initiated with improvement of her symptoms and hematologic abnormalities However, five days after discharge, the patient returned because of a recurrent headache and emesis and a falling platelet count to 23,000 per cubic millimeter. Blood cultures now showed β-hemolytic group C streptococcus. A transesophageal echocardiogram revealed ruptured chordae tendineae of the mitral-valve leaflet, possible leaflet perforation, a thickened posterior leaflet, and severe regurgitation. This suggests infective endocarditis, not thrombotic thrombocytopenic purpura, as the unifying diagnosis. This case discussion examines have clinical presentation prompted the incorrect diagnosis and asks as the correct diagnosis should be made earlier.