To the Editor, Thrombotic thrombocytopenic purpura (TTP) is a rare but fatal disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, neurologic disturbances, renal abnormalities and fever. It is now recognized that congenital and acute acquired TTP are due to a deficiency of von Willebrand factor (vWF) cleaving protein, also known as ADAMTS13, which inhibits vWF-dependent platelet aggregation [1]. Acquired thrombotic microangiopathy comprises about 40 % of all cases of TTP, including pregnancy, drugs, HIV infection, hematopoietic stem cell transplantation, autoimmune diseases or malignancies. The malignancies associated with TTP are usually solid tumors. TTP as first manifestation of multiple myeloma is very rare. To our knowledge, there is only one documented case in the literature [2]. Here we report a case of multiple myeloma, which initially presented with TTP. A 61-year-old male presented to local county hospital with a 2-month history of fatigue, jaundice and chest pain. Laboratory tests showed white blood cell of 4.9 9 10/L, hemoglobin (Hb) of 74 g/L, platelet count of 53 9 10/L, total bilirubin (TBIL) of 100.1 lmol/L (reference range 5.0–16.7 lmol/L) and direct bilirubin (DBIL) of 11.8 lmol/ L (0–5.7 lmol/L). On the third day after admission, he developed confusion, disorientation and delirium at night. Subsequently, he was transferred to our hospital for further diagnosis and treatment on December 8, 2010. Physical examination showed pale face, jaundice and somnolent with loss of orientation. No focal neurological deficit was present. Laboratory tests showed Hb of 75 g/L, platelet count of 52 9 10/L, reticulocytes of 11 %, TBIL of 103.9 lmol/L (reference range 5.1–17.1 lmol/L), DBIL of 51.8 lmol/L (0.0–6.0 lmol/L), serum lactate dehydrogenase (LDH) of 447.8l/L(reference range 109.0–245.0l/L) and blood urea nitrogen (BUN) of 8.2 mmol/L (reference range 2.90–7.14 mmol/L), creatinine(Cr) of 144.8 mmol/L (reference range 40.0–133.0 mmol/L). Serum protein electrophoresis was normal. Serum immunoglobulins, calcium and urinary Bence Jones protein was in normal range. The coagulation tests (prothrombin time, activated partial thromboplastin time, fibrinogens) and blood ammonia were within normal limits. Direct Coomb’s test was negative. Tests for HIV, Hepatitis B, Hepatitis C and autoimmune serologies were negative. Cranial computed tomography and magnetic resonance imaging remained normal. Bone marrow aspiration showed increased plasma cells of 50 % with matureappearing. His blood smear displayed schistocytes of 64/1,000. ADAMTS-13 activity was 29.9 % (reference 40–140 %). A diagnosis of TTP was made. Plasmapheresis was emergently initiated followed by fresh frozen plasma infusions of 300 mL daily with concomitant 10 mg intravenous dexamethasone per day for 6 days, then the patient was on regimen of oral prednisone of 45 mg per day with a gradual reduction. Dramatic response was observed after three plasma exchanges with 1.5 times of total plasma volumes. Clearness of mind, improvement in his chest pain, reticulocytes decreased to 3.9 % and TBIL, DBIL, LDH became normal. His platelet count was 70 9 10/L, and Hb was 80 g/L. Because the presence of plasma cell infiltration in the patient’s bone marrow biopsy, the diagnosis of multiple myeloma was highly suspected. Tests for monoclonal paraprotein were repeated performed, and the results were Xiang Xiao and Hai-ying Zhong contributed equality to this study.