Evaluation of children with macrocytosis: clinical study

Introduction in this study, it is aimed to emphasize the causes and importance of macrocytosis in paediatric practice. Methods in the paediatric hematology and oncology clinic, 1752 patients evaluated in 2017, patients with macrocytosis were examined retrospectively with clinical and laboratory findings. Patients with macrocytosis were compared with the frequency of severe hematologic diseases such as acute leukemia and bone marrow failure in patients with normocytic and microcytic mean corpusculer volume. Results macrocytosis was detected in 72 out of 1752 patients (4.1%) in the study. Acute lymphoblastic leukemia in 11(15.2%), acute myeloid leukemia in 3(4.1%), Fanconi aplastic anemia in 7(9.7%), Diamond-Blackfan anemia in 2(2.7%), aplastic anemia in 1(1.3%), congenital diseritropoetic anemia in 1(1.3%), deficiency of vitamin B12 in 14(19.4%) were diagnosed. Down syndrome was presented in 33 cases (45.8%). The number of patients with acute leukemia diagnosis was 14(0.8%) in the group in which the mean corpusculer volume was either microcytic or normocytic. The incidence of acute leukemia and bone marrow failure was significantly higher in the group with macrocytosis compared between the two groups. Conclusion although vitamin B12 deficiency is considered firstly in patients who have undergone cytopenia and macrocytosis in our country, haematological malignancies, bone marrow failures, myelodysplasia and myeloproliferative diseases should be remembered especially in the individuals with Down syndrome at the same time.


Introduction
Erythrocytes are classified into three morphological groups by their mean cell volume (MCV): microcytic, normocytic, and macrocytic.
Macrocytosis is the enlargement of erythrocytes more than 2 standard deviations than the normal value of the age group. The classification by MCV also constitutes the foundation of anemia classification used mostly in clinical practice. Although MCV values vary by age and sex, reticulocyte count and other series are considered important for the examination of patients [1]. Macrocytic anemias are classified into two groups: one is associated with the megaloblastic changes in bone marrow and the other is non-megaloblastic anemia characterized by macrocytosis. Ninety five percent of megaloblastic anemias are caused by deficiency of vitamin B12 and/or folate. Whereas the most frequent causes of non-megaloblastic macrocytosis are neonatal period, reticulocytosis, liver dysfunction, aplastic anemias, and myelodysplastic syndromes [2,3]. The aim of the present study is to underline the causes and significance of macrocytosis in clinical paediatric practice in Pamukkale University Faculty of Medicine and Diyarbakir Children Hospital Paediatric Hematology-Oncology clinics.

Methods
Retrospective analysis of the clinical and laboratory findings of 1752 patients, who were examined in the paediatric hematology and oncology outpatient clinics in a one year period during January-December 2017 were included. To identify the etiology, blood count, peripheral smear, bone-marrow aspiration and biopsies, erythrocyte sedimentation rate, kidney-liver-thyroid function tests, a-fetoprotein (AFP), hemoglobin F (HbF), vitamin B12 and folate levels were evaluated. Patients whose MCV values were more than 2 standard deviations than the normal value of the age group were grouped in macrocytosis. Etiology was investigated in these patients. There was any exclusion criteria in the study and variable datas are collected from our clinic archive. Prevalence rates of any severe hematological diseases such as acute leukemia and bone marrow deficiency were compared between macrocytic and normocytic or microcytic groups.

Results
Macrocytosis was detected in 72 of 1752 patients. The mean age of patients with macrocytosis were 5.7 (3 months to 17 years) years and 44(61.2%) were male and 28(38.2%) were female. Eleven patients  Table   1). The number of patients diagnosed with acute leukemia was 14(0.8%) in microcytic or normocytic group (n=1680) by MCV values.
Although patients with pancytopenia or bicytopenia caused by infections were included, they were not given the diagnosis of bone marrow deficiency. In the comparison of the macrocytic group to microcytic or normocytic group by MCV values, the prevalence of acute leukemia and bone marrow deficiency was found significantly higher in macrocytosis group (p< 0.001) ( Table 2). In the evaluation of the patients with Down syndrome within itself, of 106 patients with DS, 33(33.1%) had macrocytosis. Two patients with macrocytosis were diagnosed with AML-M6 and ALL at the time of the first admission. One patient was diagnosed with myelofibrosis based on bone marrow biopsy examined upon cytopenia and hypocellularity of bone marrow aspiration confirmed at outpatient follow up visit. This patient developed AML-M7, identified at follow up after 7 months. The comparison between the groups with and without macrocytosis showed that the prevalence of acute leukemia was significantly higher in patients with DS (Table 3).

Discussion
Macrocytosis is caused by four main mechanisms. These include nutritional deficiencies, bone marrow disorders, medication, and chronic diseases [4]. Macrocytosis is rarely observed in children compared to normocytic or microcytic conditions, based on MCV [5].
In our study, the prevalence of macrocytosis was 4. of MCV decreases to 85 fL; over 6 months of age, the upper limit is calculated with MCV=84+0.6xAGE formula [8]. Patients in neonatal period were not included in our study. Individuals with Down syndrome also constitute a patient group with high prevalence for macrocytosis. In evaluation studies, macrocytosis was the most frequently obtained hematological finding in DS [9]. In a study by Macrocytosis may be encountered as the earliest symptom in bone marrow deficiencies, and in MDS. Macrocytosis may be detected even in cases with normal blood count, and responsive to treatment [12].
Macrocytosis and thrombocytopenia FAA are the most frequently obtained laboratory findings. Cytopenias usually occur at around the age of 5-10 years with a mean age of 7. In patients presenting with a congenital anomaly, and growth and developmental delay, if macrocytosis is present in blood count, then FAA should be suspected [13]. DBA and CDA are bone marrow deficiency syndromes, of which the former is associated with erythroid cell aplasia, and the latter is characterized by morphological abnormalities in erythrocytes and by ineffective erythropoiesis that affects isolated erythroid series.
Majority of the patients have macrocytic anemia [14]. In our study, seven FAA, two DBA, one aplastic anemia, and one CDA patient had cytopenia and macrocytosis in their blood counts performed for diagnostic assessment (Table 1) Anemia usually takes the form of normochromic normocytic anemia accompanied with reticulocytopenia [14]. In our study, of 28 patients diagnosed with acute leukemia, 14 (50%) had macrocytosis, and 14 (50%) had microcytic or normocytic MCV values. The prevalence for acute leukemia was higher in patients with macrocytosis (Table 2).
Compared to normal population, children with DS have an increased risk of developing acute leukemia and MDS [15]. Majority of the patients with lymphoid leukemia show immuno-phenotypic features of precursor B cell ALL. In patients with DS, unlike the myeloid leukemia, lymphoid leukemias are not observed during the period of infancy. Due to intrinsic drug resistance and treatment related mortalities, prognosis was worse than that of lymphoid leukemia, which occurs sporadically [16,17]. The incidence of AML was found to be 150 times more in children with DS. The most common form of AML in children with DS is the AML-M7 acute mega karyoblastic leukemia [18]. AML-M6 and AML-M1/M2 are less frequent than AML-M7 in patients with DS [19,20]. In our 106 cases with DS, three of them developed acute leukemia. They were diagnosed with AML-M6, AML-M7 and ALL. Within the patients with DS, comparison between the groups with and without macrocytosis showed a significantly higher incidence of acute leukemia (Table 3).

Conclusion
Macrocytosis is a significant symptom in the diagnosis of bone marrow

Competing interests
The authors declare no competing interests.

Authors' contributions
All authors participated in the design of the study. Hakan Sarbay performed the collection, statistical analysis and interpretation of the data. Yılmaz Ay participated to the interpretation of data. All authors have read and approved the final document.      Chi-square test