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.

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.