Myelodysplastic syndrome (MDS) associated with EBV infection in a pediatric patient

Esther Manor, Yonat Shemer-Avni, Sophia Boriakovski, Michael Kafka, Lipa Bodner, Joseph Kapelushnik

Soroka Medical Center, Department of Hematology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Soroka Medical Center, Department of Oral and Maxillofacial Surgery, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Soroka Medical Center, Department of Pediatric Hemato-Oncology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Soroka Medical Center, Faculty of Health Sciences, Institute of Human Genetics, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Soroka Medical Center, Laboratory for Viral Diagnosis, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

DOI: 10.4236/ojped.2013.31006                

Abstract

Background: Epstein Barr Virus (EBV) is associated with different kinds of tumors. In the present study we tried to understand its role in pediatric MDS of a 4-year-old girl with EBV infection and MDS with refractory anemia and monosomy 7. Procedures: The work-up included: hematological tests; serology for IgM, IgG antibodies to EBV; PCR for EBV; cytogenetics of bone marrow (BM), and FISH analysis of BM and blood; immunohistochemistry-LMP1 expression on BM smears. Results: Hematological follow up showed constant mild dysplastic changes mostly in the erythroid lineage. PCR for EBV showed positive results in the nasopharygeal smears as well as in blood 15 weeks after disease onset. Cytogenetic analysis showed monosomy7 inall the mitoses of BM sample. Fluorescence in situ hybridization (FISH) showed monosomy 7% in 57% of the cells, followed by a decreased tendency in the percentage of monosomy 7 cells in both BM and blood. Immunohistochemistry for EBV-latent membrane protein 1 (LMP-1) on the patient’s BM smears, 21 weeks post disease onset, showed 9% positive cells, 80% of them carried monosomy 7. Conclusion: The parallel occurrence of the EBV infection and MDS, as well as the continuous EBV PCR positive and monosomy 7, support the possibility that they are related.

Keywords

Pediatric, MDS, EBV Infection

1. INTRODUCTION

Myelodysplastic syndrome (MDS) represents a heterogeneous clonal hematopoetic stem cell disorder characterized by ineffective hematopoiesis and increased risk of transformation to MDS-related leukemia. MDS is uncommon in children and accounts for less than 5% of all hematopoetic neoplasms [1].

Monosomy 7 is the most common chromosomal aberration in MDS [2-6]. It implies a rather poor prognosis that is associated with high risk of transformation to acute leukemia [7]. The age distribution is 2 - 5 years with male predominance of 70% - 80% [8]. There are also reports on familial MDS with monosomy 7. Familial monosomy 7 is defined when at least two siblings are found to carry monosomy 7 associated with pre-leukemic or leukemic manifestations [9].

Epstein Barr Virus (EBV) is one of the causative agents of infectious mononucleosis and the first described human tumor virus. EBV was discovered in Burkitt’s lymphoma tumor cells, characterized by t(8,14), t(2,8), and t(8,22) [10]. It has also been found to be associated with post-transplant lymphoproliferative disorders (PTLD) and with malignancies such as, Hodgkin’s lymphoma (HD) and nasopharyngeal carcinoma (NPC) [11,12].

EBV’s latent membrane protein (LMP1) gene is considered the main viral oncogene driving cell growth, promoting metastases, apoptotic resistance, and immune modulation, including blockade of interferon alpha-induced antiviral signaling [13].

Infection with EBV can produce symptoms closely resembling those seen in patients with MDS. This raises a question regarding the diagnosis of malignant disease in cases of MDS in children with EBV infection [14-16] and the role of EBV in MDS pathogenesis: Does EBV infection mimic childhood MDS? Does it trigger or enhance childhood MDS onset? Is EBV the etiology of MDS or is MDS onset with EBV infection just coincidental?

Here we present results that might support the possibility that EBV plays a role in pediatric MDS of a 4year-old girl with monosomy 7.

2. CASE REPORT AND RESULTS

A 4-year-old girl was admitted to the pediatric department with suspected anemia, after experiencing two episodes of fever about 3 weeks earlier. Upon admittance she was weak and pale with a diagnosis of infectious mononucleosis by the family doctor, although no tests were undertaken. According to her mother’s anamnesis, she had been suffering on and off from viral and bacterial infections.

Hematology: Peripheral blood count showed a white blood count (WBC) of 4400/μl with no blasts, Hb of 4.9 g/dl, and platelet count of 175,000/μl. The clinical impression was of erythroblastopenia of childhood, probably related to viral infection. Serial transfusions of packed cells elevated the Hb to 6.4 g/dl. Peripheral blood count was followed and transfusions of packed cells were given due to the anemia.

Serology: The work-up revealed positive antibodies to cytomegalovirus (CMV) IgM and IgG, with high avidity. Antibodies to EBV (viral capsid antigen) VCA IgG and IgM were positive; however, IgG antibodies to EBV nuclear antigen (EBNA) were negative. These results indicate that the patient was suffering from an acute primary EBV infection with possible CMV reactivation. EBV acute infection was further confirmed by EBV-positive PCR results of the pharyngeal smear.

Cytogenetics: Cytogenetic analysis of bone marrow (BM) was performed according to standard methods. BM cells were cultured for 24 hours using methotrexate for synchronization. About 15 metaphases were analyzed using G-band staining. Karyotypes were assigned according to the International System for Human Cytogenetic Nomenclature (ISCN 2009) guidelines [17].

FISH analysis was performed according to the manufacturer’s instructions using an LSI D7S522 (7q31) spectrum orange/CEP spectrum green (VYSIS) probe. More than 500 cells were analyzed.

Virology tests: IgM and IgG antibodies to EBV VCA and EBNA, and to CMV, as well as avidity were tested using Liaision Technologies, according to the manufacturer’s instructions (Liaison Technologies, Perugia, Italy).

Viral load for EBV DNA was tested as described by Niesters et al. [18].

Immunohistochemistry: LMP1 expression on BM smears were examined using the Ivew DAB detection kit (Ventana Medical Systems, Inc., Tucson, AZ) using monoclonal mouse anti-Epstein Barr Virus, LMP clones CS 1-4 (DakoCytomation, Denmark), and FISH analysis using the LSI D7S522 (7q31) spectrum orange/CEP spectrum green (VYSIS) probe. More than 800 cells were examined.

Figure 1 depicts the antibody responses to IgM, IgG against EBV’s viral capsid antigen (VCA), and EBV’s nuclear antigen (EBNA) at time intervals from 2 weeks to 6 months after onset of the disease. It shows a three-fold increase in the level (antibody titer) of VCA’s IgG antibodies at 6 weeks after disease onset, while the humeral immune response to EBNA, a classic pattern of EBV acute infection, increases about 6 months after disease onset. The IgM response to VCA gradually declined over three months.

Although no EBV DNA could be detected in the first blood sample, which was taken 3 weeks post-disease onset, EBV DNA was present when tested in a nasopharyngeal smear 12 weeks after disease onset as well as in blood samples. EBV viral load at 15, 29, and 42 weeks post-illness onset were >25, 100, and 100 copies/ml, respectively.

2.1. Hematologic Tests

At admission complete blood count showed mild leukopenia (4400/ul) and neutropenia (900/ul), severe anemia (5.0 g/dl), normal RBC indices, elevated RDW, and normal PLT count. CBC tests performed during the one-year follow up demonstrated mostly leukocyte counts of 4300 - 5600/μl (normal low level of 5000/ul) and neutropenia of 770 - 1440/μl (normal low level of 1500/μl). During the first 6 months of treatment the patient received a total of 7 units of packed red blood cells. Following the transfusion of every unit, the Hb level was raised to 10.0 - 11.0 g/dl; however, rapidly falling afterwards (Figure 2). After this period the Hb level gradually and constantly increased without need for additional blood transfusions. PLT count remained normal during ing the one-year follow up period. The first two samples demonstrated mild monocytosis with few immature cells, possibly a result of a reactive process. However, a constant finding during the whole year was mild dysplastic changes, mostly in the erythroid lineage, which included the presence of macronormoblasts, and few bi-nucleated normoblasts or cells with nuclear budding/karyorrhexis. In the megakaryocytic lineage, hypolobularity and/or separate nuclear lobes were detected. Peripheral blood smears examined in parallel with BM aspirates demonstrated mild to moderate anisocytosis with or without the presence of single normoblasts.

Figure 1. Antibody responses to EBV during the time course of the infection. IgM (diamonds) and IgG (squares) antibodies to VCA, as well as antibodies to EBNA (triangle, EBNA-G) were tested in the patient’s sera starting two weeks after initial symptoms. The cut-off values were: VCA-M > 40, positive; VCA-G/EBNA-G > 20, positive. Black arrows represent EBV-DNA positive samples, taken from the larynx.

Figure 2. Blood count anemia parameters. Hemoglobin (HB), Hematocrit (HCT), and red blood cell count (RBC) during 40 weeks post-disease onset. Transfusion of packed cells has been given to the patient noted by the arrows. Normal values: Hemoglobin (HB): 11.5 - 13.5 g/dl, Hematocrit (HCT): 34% - 40%, Red blood cells (RBC): 4.2 - 5.4 × 10⁶. Arrows: transfusion of packed cells.

Figure 2 shows the results of the absolute neutrophilic count (ANC) and Hemoglobin (Hb) during the 55 weeks post-disease onset. Transfusions of packed cells given to the patient are noted by arrows. No significant abnormalities were found in all other hematology parameters.

Conflicts of Interest

The authors declare no conflicts of interest.

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