Pseudothrombotic microangiopathy and pancytopenia as a rare presentation of vitamin B12 deficiency

ABSTRACT

Case Report A 62-year-old male presented to our hospital with a few days of worsening dyspnea, associated with numbness in the left lower extremity, dizziness and transient brief chest pain that was described as a sharp intermittent pain. He denied any fever, chills, nausea, vomiting, diarrhea, headache, or recent ill contacts. The patient also denied any family history of blood or bone morrow disease. He had been released from incarceration 2 days prior to the presentation. Complete blood count revealed pancytopenia with hemoglobin of 6.8 g/dL, MCV of 112 fL, white blood cell count of 1.2 K/uL, and platelet count of 78 K/uL. The patient was transfused with packed red blood cells and then admitted to the inpatient medicine ward for further treatment and evaluation. Blood smear confirmed the pancytopenia with severe neutropenia, macrocytosis, and moderate thrombocytopenia. In addition, it showed erythrocytes with marked poikilocytosis including occasional schistocytes and teardrop cells. His lab investigations were notable for B12 level below 150 pg/mL (Normal range 211-911), fibrinogen of 144 mg/dL , haptoglobin less than 10 mg/dL, LDH of 1013 U/L. Other lab studies including troponin, ferritin, TIBC, serum iron, vitamin B1, PT/INR, PTT, SPEP, COVID-19, EBV, CMV, HIV, Hepatitis A, B, and C were all unrevealing. Abdominal ultrasound was significant for splenomegaly. CT head and chest xray were unremarkable. After starting treatment with cobalamin therapy, the patient has shown improvement in terms of cell counts, resolution of hemolysis. He also reported significant improvement in tingling and dizziness. All this confirms the diagnosis. Vitamin B12 deficiency manifestations can vary between asymptomatic, mild, and severe. In our case, the patient presented with pseudothrombotic microangiopathy and pancytopenia. Both are rare and serious manifestations of vitamin B12 deficiency. Physicians should be aware of cobalamin deficiency as one of the etiologies for pancytopenia and pseudothrombotic microangiopathy. Therefore, an early recognition and treatment is crucial. (Figure Presented).