Vitamin B₁₂ deficiency-induced pseudothrombotic microangiopathy without macrocytosis presenting with acute renal...

Vitamin B₁₂ deficiency-induced thrombotic microangiopathy, known as pseudothrombotic microangiopathy, is a rare condition which resembles the clinical features of thrombotic thrombocytopenic purpura but requires a markedly different treatment. Most cases of vitamin B₁₂ deficiency have only mild hematological findings, but in approximately 10% of patients life-threatening conditions have been reported.

We report a case of a 46-year-old Moroccan man presenting with severe hemolytic anemia, thrombocytopenia, and renal failure in absence of macrocytosis, thus mimicking a genuine thrombotic thrombocytopenic purpura. Rapid improvement of renal function observed with only hydration and transfusions of packed red blood cells and the presence of pancytopenia suggested a bone marrow deficiency associated to a hemolytic component of unclear origin. Detection of low levels of vitamin B₁₂ and rapid restitutio ad integrum with its replacement supported the diagnosis of pseudothrombotic thrombocytopenic purpura caused by vitamin B₁₂ deficiency.

Diagnosis of pseudothrombotic thrombocytopenic purpura caused by vitamin B₁₂ deficiency might be difficult. Awareness of clinicians toward this differential diagnosis might spare patients from unnecessary therapeutic plasma exchange that is burdened by morbidity and mortality.