Pancytopenia and TTP-like picture secondary to pernicious anaemia

A 21-year-old man presented to the emergency department with generalised weakness, weight loss and decreased appetite for few weeks. He had evidence of severe pancytopenia and haemolysis. His peripheral smear with many schistocytes was suspicious for thrombotic thrombocytopenic purpura (TTP). He was supported with blood transfusions and daily plasmapheresis. His platelet counts worsened despite 4 days of therapy. Bone marrow biopsy was significant for hypercellular bone marrow with megaloblastic changes. Further workup revealed normal ADAMTS13 level, low vitamin B₁₂, positive intrinsic factor antibodies and high methylmalonic acid. Diagnosis of pernicious anaemia was established and he was started on daily treatment with intramuscular vitamin B₁₂ which subsequently improved his symptoms and haematological parameters. This report highlights the importance of checking vitamin B₁₂ level in patients presenting with pancytopenia and TTP-like picture before making a diagnosis of TTP.