Thrombotic Thrombocytopenic Purpura Without Schistocytes: Beware of Misdiagnosis

Abstract

A 43-year old woman was admitted for acute unusual headache, vertigo and left upper limb weakness. She had been complaining of asthenia for the past few weeks. Past medical history included uterine cervix cancer treated with conisation and two pregnancies without serious complications. No allergy or recent drug introduction was noted. After ruling out current pregnancy, Magnetic Resonance Imaging (MRI) was immediately performed and showed recent ischemic strokes in multiple territories. Doppler ultrasound imaging showed no carotid or vertebral arteries lesion. Electrocardiogram showed no ST elevation or atrial fibrillation and echocardiography did not reveal embolic lesion or patent foramen ovale. Blood cell count showed thrombocytopenia at 17 x 10⁹/L (confirmed in citrate tube) and hyperleukocytosis at 18 x 10⁹/L without anemia (hemoglobin at 12,9 g/dL). Basic metabolic profile, kidney and liver function tests were normal. Hemolysis signs were present: reticulocytes, total bilirubin, Lactate dehydrogenase (LDH) and haptoglobin levels were at 147 x 10⁹/L, 27,2 μmol/L, 454 U/L and bellow 0.08 g/L respectively. Repeated blood smears showed no schistocytes. A disseminated intravascular coagulation was ruled out (normal APTT and prothrombin time, fibrinogen at 3,6 g/L), as well as autoimmune cytopenia (Coombs test was negative), hyperhomocysteinemia, vitamin deficiencies (B9, B12) and paroxysmal nocturnal hemoglobinuria. Bone marrow examination showed increased megakaryocytes with normal morphology excluding a central origin. Lupus anticoagulant (LA), anticardiolipin (aCL) and anti- β2gp1 antibodies were negative. A thoraco-abdominopelvic scan with contrast showed small renal and splenic infarcts; no suspect tumor was observed.