Adult Vitamin B12 Deficiency-Associated Pseudo-Thrombotic Microangiopathy: A Systematic Review of Case Reports.

Cobalamin-deficient thrombotic microangiopathy or vitamin B12 deficiency presenting as pseudo-thrombotic microangiopathy is a rare disorder that can be misdiagnosed as thrombotic thrombocytopenic purpura. Patients with this condition are at risk of receiving unnecessary plasmapheresis with a potential delay in appropriate therapy with vitamin B12 supplementation. There are no established diagnostic criteria for this condition in clinical practice. We performed a systematic review of case reports published between January 2018 and January 2023 to analyze the clinical characteristics, risk factors, and patterns of laboratory markers to improve the diagnostic criteria for this condition.

Concomitant Vitamin B1 and Vitamin B12 Deficiency Mimicking Thrombotic Thrombocytopenic Purpura.

Vitamin B12 deficiency-induced pseudo-thrombotic thrombocytopenic purpura (pseudo-TTP) is a rare condition. In reported literature, most cases were due to pernicious anemia (confirmed by the presence of anti-parietal cells or anti-intrinsic factor antibodies). Nutritional vitamin B12 deficiency causing pseudo-TTP is a much rarer entity. Differentiating thrombotic thrombocytopenic purpura (TTP) cases from pseudo-TTP (from any cause) should be done as soon as possible since the etiology, treatment, and outcome are different. Hematological findings from pseudo-TTP (when associated with vitamin B12 deficiency) respond to B12 replacement but do not respond to plasmapheresis. Neurological symptoms are one of the criteria for TTP, and altered mentation or psychosis in these cases is presumed secondary to either TTP or vitamin B12 deficiency. However, neurological symptoms are more characteristic of TTP rather than pseudo-TTP. In the rarer subsets of patients concerned with nutritional deficiency and neuropsychiatric symptoms, prompt consideration of concomitant vitamin B1 deficiency and Wernicke encephalopathy is essential. Immediate empiric treatment with high-dose IV thiamine should be started. If unrecognized and left untreated, thiamine deficiency can cause rapid progression to irreversible neurological symptoms, coma, and death, despite hematological improvement with B12 replacement. We report a rare case of concomitant vitamin B12 and vitamin B1 deficiency presenting with confusion, severe hemolytic anemia, acute renal failure, diarrhea, and thrombocytopenia mimicking TTP.