[False Moskowitz disease, true Biermer disease]

Pernicious Anemia Associated Cobalamin Deficiency and Thrombotic Microangiopathy: Case Report and Review of the Literature

A 43-year-old Hispanic male without significant previous medical history was brought to emergency department for syncope following a blood draw to investigate a 40 lbs weight loss during the past 6 months associated with decreased appetite and progressive fatigue. The patient also reported a 1-month history of jaundice. On examination, he was hemodynamically stable and afebrile with pallor and diffuse jaundice but without skin rash or palpable purpura. Normal sensations and power in all extremities were evident on neurological exam. Presence of hemolytic anemia, schistocytosis, thrombocytopenia, and elevated lactate dehydrogenase (LDH) was suggestive of thrombotic thrombocytopenic purpura (TTP). However, presence of leukopenia, macrocytes, and an inadequate reticulocyte response to the degree of anemia served as initial clues to an alternative diagnosis. Two and one units of packed red blood cells were transfused on day 1 and day 3, respectively. In addition, one unit of platelets was transfused on day 2. Daily therapeutic plasma exchange (TPE) was initiated and continued until ADAMTS-13 result ruled out TTP. A low cobalamin (vitamin B12) level was evident at initial laboratory work-up and subsequent testing revealed positive intrinsic factor-blocking antibodies supporting a diagnosis of pernicious anemia with severe cobalamin deficiency. Hematological improvement was observed following vitamin B12 supplementation. The patient was discharged and markedly improved on day 9 with outpatient follow-up for cobalamin supplementation.

Therapeutic dilemma in the management of a patient with the clinical picture of TTP and severe B12 deficiency

Background

Idiopathic thrombotic thrombocytopenic purpura (TTP) is a rare hematological emergency characterized by the pentad of microangiopathic hemolytic anemia, thrombocytopenia, neurological symptoms, renal injury, and fever that is invariably fatal if left untreated. Prompt intervention with plasma exchange minimizes mortality and is the cornerstone of therapy. Rare reports have described “pseudo-TTP” driven by extreme hematologic abnormalities resulting from deficiency of vitamin B₁₂. Distinguishing between these entities can pose a diagnostic and therapeutic challenge.

Case presentation

A 77 year old female presented with altered mental status, renal insufficiency, thrombocytopenia and evidence of microangiopathic hemolytic anemia, suggesting TTP. Workup demonstrated macrocytosis and reticulocytopenia, and B₁₂ level was unmeasurably low. Other elements of her clinical presentation, including volume loss and bleeding suggested a multifactorial pathogenesis could be contributing to her laboratory abnormalities, reducing the likelihood that she had TTP. The risks and benefits of treating aggressively with therapeutic plasma exchange (TPE) for TTP were considered given the diagnostic possibilities. The patient received TPE initially, with rapid de-escalation after her clinical response suggested “pseudo-TTP” from B₁₂ deficiency was the driving the process. B₁₂ supplementation corrected her hematologic abnormalities and she remains well two years after presenting.

Conclusions

TTP is a rare condition with fatal consequences if left untreated. Guidelines recommend TPE even if there is uncertainty about the diagnosis of TTP. B₁₂ deficiency is common, though not typically associated with severe hematologic abnormalities. We compare the presenting characteristics of all thirteen cases of pseudo-TTP reported in the literature with those from patients in case series of TTP to suggest a set of parameters that can help clinicians distinguish between pseudo-TTP and TTP and guide decision making regarding intervention. Evaluation of all TTP cases should include a B₁₂, methylmalonic acid level and reticulocyte count. Reticulocytopenia suggests B₁₂ deficiency. Finally an LDH level above 2500 IU/L is relatively uncommon in TTP and should suggest consideration of B₁₂ deficiency.

Current hematological findings in cobalamin deficiency. A study of 201 consecutive patients with documented cobalamin deficiency

With the introduction of automated assays for measuring serum cobalamin levels over the last decades, the hematological manifestations related to cobalamin deficiency have been changed from the description reported in 'old' studies or textbooks. We studied the hematological manifestations or abnormalities in 201 patients (median age: 67 +/- 6 years) with well-documented cobalamin deficiency (mean serum vitamin B12 levels 125 +/- 47 pg/ml) extracted from an observational cohort study (1995-2003). Assessment included clinical features, blood count and morphological review. Hematological abnormalities were reported in at least two-third of the patients: anemia (37%), leukopenia (13.9%), thrombopenia (9.9%), macrocytosis (54%) and hypegmented neutrophils (32%). The mean hemoglobin level was 10.3 +/- 0.4 g/dl and the mean erythrocyte cell volume 98.9 +/- 25.6 fl. Approximately 10% of the patients have life-threatening hematological manifestations with documented symptomatic pancytopenia (5%), 'pseudo' thrombotic microangiopathy (Moschkowitz; 2.5%), severe anemia (defined as Hb levels <6 g/dl; 2.5%) and hemolytic anemia (1.5%). Correction of the hematological abnormalities was achieved in at least two-thirds of the patients, equally well in patients treated with either intramuscular or oral crystalline cyanocobalamin. This study, based on real data from a single institution with a large number of consecutive patients with well-documented cobalamin deficiency, confirms several 'older' findings that were previously reported before the 1990s in several studies and in textbooks.