Megaloblastic anemia (MBA) is a reversible metabolic disorder that responds well to vitamin B12 supplementation. It contrasts with myelodysplastic syndrome (MDS), an irreversible neoplastic condition characterized by hematopoietic stem cell abnormalities. To date, no association has been identified between these two distinct etiologies, and they are considered independent diseases. However, despite their distinct classifications, both conditions present macrocytic anemia, similar bone marrow findings, and sometimes have common chromosomal abnormalities, which can lead to occasional misdiagnoses. Herein, we present a patient initially diagnosed with pernicious anemia (PA) who showed improvement with replacement therapy but subsequently became resistant to treatment and eventually developed MDS. Quantitative assessment of Wilm\'s tumor-1 (WT1) mRNA has emerged as a valuable tool for gauging MDS disease status and distinguishing it from related disorders, such as aplastic anemia. In our investigation of 30 patients with MBA, we explored WT1 mRNA expression. We observed its presence in 10 patients with PA, which suggests a potential link between PA and hematopoietic tumors.

The COVID-19 pandemic has resulted in substantial lifestyle changes with significant implications for nutritional health. Factors such as movement restrictions and disruptions in food supply chains led to the restricted availability of primary sources of essential micronutrients. To highlight this, we present the case of an elderly woman with an underlying subclinical cobalamin deficiency who developed symptomatic megaloblastic anemia, requiring hospital admission under lockdown conditions. This exemplifies how changes in diet during the COVID-19 lockdown have hastened the onset of B12 deficiency symptoms. Adverse outcomes can be avoided by identifying people at high risk of poor nutritional status and implementing policy initiatives that enhance their nutritional condition. This case report showed how important the B12 shortage was during the COVID-19 lockdown, especially for older people. They are more likely to be malnourished during COVID-19 for several reasons.

UNASSIGNED: In the 1940s to 1950s, high-dose folic acid supplements (>5 mg/d) were used clinically to reverse the megaloblastic anemia of vitamin B12 deficiency caused by pernicious anemia. However, this treatment strategy masked the underlying B12 deficiency and possibly exacerbated its neuropathological progression. The issue of masking and exacerbating B12 deficiency has recently been rekindled with the institution of folic acid fortification and the wide-spread use of folic acid supplements.
UNASSIGNED: The objectives of this review are to describe clinical and epidemiological evidence that excess folic acid exacerbates B12 deficiency, to summarize a hypothesis to explain this phenomenon, and to provide guidance for clinicians.
UNASSIGNED: Cognitive function test scores are lower and blood homocysteine and methylmalonic acid concentrations are higher in people with low B12 and elevated folate than in those with low B12 and nonelevated folate. High-dose folic acid supplementation in patients with pernicious anemia or epilepsy cause significant reductions in serum B12. It is hypothesized that high-dose folic acid supplements cause depletion of serum holotranscobalamin and thus exacerbate B12 deficiency.
UNASSIGNED: The evidence for excess folic acid exacerbating B12 deficiency is primarily correlative or from uncontrolled clinical observations, and the hypothesis to explain the phenomenon has not yet been tested. Nonetheless, the evidence is sufficiently compelling to warrant increased vigilance for identifying B12 deficiency in at risk individuals, including older adults and others with low B12 intake or conditions that are associated with B12 malabsorption, who also ingest excessive folic acid or are prescribed folic acid in high doses.
Plain language titleExcess Folic Acid and Vitamin B12 Deficiency: Clinical Implications?Plain language summaryIt has been known for many decades that high doses of the B vitamin supplement, folic acid, can alleviate the anemia of vitamin B12 deficiency, at least temporarily. However, by alleviating the anemia, such folic acid supplements were said to “mask” the underlying vitamin B12 deficiency, thus allowing neurological damage to continue or possibly be exacerbated. Consequently, treating vitamin B12 deficiency with high dose folic acid was discontinued in the 1970s. The issue of whether folic acid supplements can exacerbate vitamin B12 deficiency reemerged in the 1990s with folic acid fortification of cereals and grains in the United States and Canada (and now in over 80 countries around the world) to prevent spina bifida and other birth defects. This narrative review summarizes the results of studies that have assessed the relationships between folic acid and folate and vitamin B12 status in patients and in populations. A recent hypothesis on how folic acid might exacerbate vitamin B12 deficiency is summarized, and recommendations to clinicians are made for increased vigilance in assessing vitamin B12 status in certain groups at risk of vitamin B12 deficiency, including older adults, people with gastrointestinal issues and other factors that cause vitamin B12 malabsorption, people with unexplained neurological problems, and people who follow vegan or vegetarian diets which are naturally low in vitamin B12.

BACKGROUND: Vitamin B12 is primarily transported from plasma to cells by Transcobalamin. Deficiency of Transcobalamin is a rare autosomal recessive disorder that results in unavailability of cobalamin in cells and accumulation of homocysteine and methylmalonic acid.
METHODS: We report a case of a 2-year-old male child with persistent pancytopenia, recurrent infections, and megaloblastic anemia. Next-generation sequencing identified a novel variant in exon 8 of TCN2 gene. Substantial improvement has been observed following administration of high doses of parenteral methylcobalamin.
CONCLUSIONS: In patients with unresolved pancytopenia and megaloblastic anemia, Transcobalamin deficiency should be investigated and treated promptly to prevent any irreversible and harmful outcome.

Megaloblastic anemia, stemming from vitamin B12 or folate deficiencies, poses diagnostic challenges due to its diverse clinical presentation. We report a case of a 25-year-old female college student presenting with symptoms indicative of megaloblastic anemia, attributed to her recent adoption of a strict vegetarian and vegan diet. Clinical manifestations included dizziness, palpitations, blurred vision, vertigo, headaches, burning sensations, excessive sweating, mouth ulcers, and unintentional weight loss. Physical examination revealed pale palpebral conjunctiva and sweating on the palms and soles. Laboratory findings confirmed megaloblastic anemia secondary to vitamin B12 deficiency, with elevated mean corpuscular volume (MCV), reticulocyte count, serum methylmalonic acid (MMA), and homocysteine levels. Treatment with intramuscular cyanocobalamin injections and oral vitamin B12 supplementation led to symptomatic improvement and normalization of hematological parameters. This case underscores the crucial role of dietary habits in hematological health. Vegetarian and vegan diets, devoid of animal products rich in vitamin B12, increase the risk of deficiency. Early recognition and management of such deficiencies are imperative to prevent long-term complications. A literature review corroborates the association between vegetarianism/veganism and megaloblastic anemia risk. Healthcare providers should vigilantly assess dietary histories, particularly in patients with hematological abnormalities. Further research is warranted to explore strategies for optimizing nutrient intake in individuals adhering to vegetarian or vegan diets, aiming to mitigate the risk of nutritional deficiencies and associated complications.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by a lack of behavioral flexibility and stereotyped language. Food selectivity is common among children with ASD because of their persnickety nature. A prolonged unbalanced diet results in an increased risk of several diseases, such as iron deficiency anemia, scurvy, rickets, dry eye, and Wernicke encephalopathy. However, no cases of megaloblastic anemia have been reported to date. We report the case of an 11-year-old boy with ASD who developed megaloblastic anemia due to vitamin B12 deficiency. He had a prolonged history of selective eating for more than 10 years. His nutritional status on admission was poor, and he had low weight and short stature. His food selectivity was so strong that intervention to expand diet variety was unsuccessful. A developmental-behavioral pediatrician found that the patient had visual dominance and could take some medications when suffering from a minor illness. Nutritional supplements were selected after consultation with a nutritionist. Although compulsory treatment was necessary during the acute phase, the therapy was continued at home. With multidisciplinary intervention tailored to the patient and his parents\' characteristics, his nutritional status improved in a few months.

Objective The objectives of this study were to determine the frequency of the clinical spectrum of diseases in patients with macrocytosis and to summarize the diagnostic evaluation of patients found to have macrocytosis on laboratory testing. Background This was a cross-sectional study that took place at the Department of Medicine in Combined Military Hospital, Rawalpindi, Pakistan, from January to June 2023. Methodology One hundred and five patients with macrocytosis with mean corpuscular volume (MCV) values > 100 fL (80 to 100 fL) were inducted as per inclusion and exclusion criteria. Informed consent was obtained from all patients. Complete blood counts (CBC), peripheral blood film, serum vitamin B12 levels, serum folate levels, renal function tests (RFTs), liver function tests (LFTs), and thyroid function tests (TFTs) were performed during the assessment. Results The commonest cause of macrocytosis was vitamin B12 deficiency followed by folate deficiency, combined vitamin B12 and folate deficiency, and other causes were also found in a few cases. Conclusion Serum vitamin B12 and folate deficiency are the most common preventable causes of macrocytosis.

BACKGROUND: Erlotinib is a first-generation, tyrosine kinase inhibitor of the epidermal growth factor receptor (EGFR-TKI) used for the treatment patients with NSCLC. Erlotinib is considered as a safe and effective treatment option, with generally good tolerance. Diarrhea and rash are the most common side effects, and more rare side effects appear in long-term real-world applications. Severe erlotinib related megaloblastic anemia is rare and remains unreported. This is the first case report of severe megaloblastic anemia in a patient with advanced lung adenocarcinoma with an EGFR L858R mutation treated with erlotinib. In this report, the clinical manifestations, diagnosis and treatment of erlotinib related severe megaloblastic anemia are described, and the possible pathogenesis and related treatment options are discussed.
METHODS: Herein, we present a 57- year-old non-smoking female diagnosed with metastatic lung adenocarcinoma harboring an EGFR L858R mutation, who had received erlotinib as the first-line therapy. After 44 weeks of treatment, the patient developed severe anemia. Anemia was manifested as megaloblastic anemia with elevated mean corpuscular volume and mean corpuscular hemoglobin. The total vitamin B12 level was below the detection limit of 50.00 pg /mL. Bone marrow smear suggested megaloblastic anemia. Her hematologic parameters were markedly recovered following the withdrawal of erlotinib and vitamin B12 supplement. As a result, the patient was diagnosed with erlotinib-associated megaloblastic anemia.
CONCLUSIONS: This is the first case of severe megaloblastic anemia reported with erlotinib. Few of these hematologic adverse effects have been observed in studies on erlotinib, this case report highlights this possibility for long-term erlotinib administration. Close clinical and blood monitoring is recommended for patients receiving long-term TKI therapy.

OBJECTIVE: Transcobalamin II (TC) promotes the cellular uptake of cobalamin (Cbl) through receptor-mediated endocytosis of the TC-cbl complex in peripheral tissues. TC deficiency is a rare disorder that causes intracellular Cbl depletion. It presents in early infancy with a failure to thrive, diarrhea, anemia, agammaglobulinemia, and pancytopenia. Data from five TC-deficient patients including clinical, biochemical, and molecular findings, as well as long-term outcomes, were collected.
METHODS: Mutation analysis revealed one unreported pathogenic variant in the TCN2 gene. One patient had exocrine pancreatic insufficiency. We conducted a retrospective analysis of C3 and C3/C2 from dried blood samples, as this is implemented for newborn screening (NBS). We detected a marked increase in the C3/C2 ratio in two samples. Treatment was based on parenteral Cbl. Three patients treated before six months of age had an initial favorable outcome, whereas the two treated later or inadequately had neurological impairment.
CONCLUSIONS: This is the first report of Argentinean patients with TC deficiency that detected a new variant in TCN2. NBS may be a tool for the early detection of TC deficiency. This data emphasizes that TC deficiency is a severe disorder that requires early detection and long-term, aggressive therapy. Accurate diagnosis is imperative, because early detection and treatment can be life-saving.

Vitamin B12 and folate deficiency are reversible causes of megaloblastic anemia. Strict vegetarians are at risk of megaloblastic anemia due to low cobalamin in their diet. Knuckle hyperpigmentation in patients with megaloblastic anemia is due to excess melanin synthesis in skin. Here we present a case of a young vegetarian male with megaloblastic anemia with knuckle hyperpigmentation managed successfully with intravenous followed by oral vitamin b12 and folate supplementation.