A case of juvenile myelomonocytic leukemia with concomitant cytomegalovirus infection

Validation of flow cytometric phospho-STAT5 as a diagnostic tool for juvenile myelomonocytic leukemia

To diagnose juvenile myelomonocytic leukemia (JMML) is sometimes challenging, because around 10% of patients lack molecular abnormalities affecting Ras-MAPK (mitogen-activated protein kinase) pathway and other diseases such as cytomegalovirus infection can mimic clinical signs of JMML. In order to validate a phospho-specific flow cytometry assay assessing phospho-signal transducer and activator of transcription factor 5 (p-STAT5) as a new diagnostic tool for JMML, we examined 22 samples from children with JMML and 47 controls. CD33+/CD34+ cells from 22 patients with JMML showed hyperphosphorylation of STAT5 induced by sub-saturating doses of granulocyte-macrophage colony-stimulating factor (GM-CSF). Using a training set of samples (11 JMML and 23 controls), we identified a threshold for p-STAT5-positive after stimulation with 0.1 ng/ml GM-CSF (17.17%) that discriminates JMML from controls. This threshold was validated in an independent series (11 JMML, 24 controls and 7 cases with diseases other than JMML) where we demonstrated that patients with JMML could be distinguished from other subjects with a sensitivity of 91% (confidence interval (CI) 59–100%) and a specificity of 87% (CI 70–96%). Positive and negative predictive values were 71% (CI 42–92%) and 96% (CI 82–100%), respectively. In conclusion, flow cytometric p-STAT5 profiling is a reliable diagnostic tool for identifying patients with JMML and can contribute to consistency of current diagnostic criteria.

Aberrant phosphorylation of STAT5 by granulocyte-macrophage colony-stimulating factor in infant cytomegalovirus infection mimicking juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) progenitor cells exhibit in vitro hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF). Phospho-specific flow cytometry using anti-phosphorylated STAT5 antibody is a new method recently reported to detect GM-CSF hypersensitivity of cells. However, colony assays using methylcellulose medium to measure GM-CSF-hypersensitivity remain as the current gold standard. Interestingly, cytomegalovirus (CMV) infection in infancy often presents with a variety of clinical symptoms that mimic JMML, with CMV giving a positive result by colony assay. We wanted to determine whether aberrant STAT5 activation occurs in CMV infection by using phospho-specific flow cytometry, and to ascertain whether this method is effective at discriminating CMV infection from JMML. Peripheral blood mononuclear cells from patients with JMML and CMV infection displayed an elevated proportion of p-STAT5 cells after low-dose GM-CSF stimulation when compared with cells from normal individuals. However, we found no significant differences in the percentage of p-STAT5 positive cells from patients with CMV infection and JMML at any doses of the GM-CSF doses used. We conclude that patients with CMV infection cannot be discriminated from patients with JMML by this new diagnostic method.

Diagnostic dilemma of JMML coexisting with CMV infection

Juvenile myelomonocytic leukemia (JMML) is a rare mixed myeloproliferative and myelodysplastic disorder of early childhood, characterized by excessive proliferation of monocytic and granulocytic cells, along with myelodysplastic features. There are reports of viral infections mimicking JMML, with all clinical and hematological parameters normalizing on resolution of infection. The authors describe a 1- year- old boy with concomitant JMML and CMV infection. The diagnostic dilemma, the significance of distinguishing it from a mimicking viral infection, as well as potential synergistic effect of concomitant infections on the presentation or actual disease severity of underlying JMML will be discussed.

Juvenile myelomonocytic leukemia presenting with coexistent cytomegalovirus infection--a case report

We report a case of juvenile myelomonocytic leukemia (JMML) with coexistent cytomegalovirus (CMV) infection in a 10-month-old child that caused initial diagnostic dilemma. The patient presented with fever, anemia, lymphadenopathy, and hepatosplenomegaly. The peripheral blood smear and bone marrow aspirate examination showed monocytosis, leukoerythroblastosis, myeloid hyperplasia, and increased blasts. Serologic test for CMV was positive and thus the hematologic picture was attributed to CMV infection and gancyclovir was started. The patient, however, did not improve clinically. A repeat peripheral smear and marrow showed persistence of the above picture and a diagnosis of JMML was made. Viral infections in young children may present with hematologic features overlapping with JMML and simultaneous occurrence of both may cause diagnostic dilemma.

Cytomegalovirus infection mimicking juvenile myelomonocytic leukemia showing hypersensitivity to granulocyte-macrophage colony stimulating factor

We describe an infant with cytomegalovirus (CMV) infection presenting as transient myeloproliferation resembling juvenile myelomonocytic leukemia (JMML). The patient fulfilled the international diagnostic criteria of JMML, including hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF). Viral studies using serologic assays and polymerase chain reaction (PCR) were positive for CMV. Clinical symptoms disappeared and laboratory values returned to normal without specific treatment within 1 year. Follow-up showing a decrease in viral titers suggested CMV infection as an etiologic factor for the development of myeloproliferative features. We conclude that the CMV infection transiently induced abnormal myelopoiesis in this infant.

Temporary blast reduction after immunoglobulin administration for congenital cytomegalovirus infection masking infant leukemia with cryptic MLL rearrangement

Differentiation between reactive bone marrow suppression due to viral infection and early stages of leukemia can be difficult particularly in young infants. We report on a 2-month-old girl presenting with pancytopenia and positive markers for congenital cytomegalovirus (CMV) infection. Definitive diagnosis of coexisting pro-B cell infant leukemia with cryptic MLL rearrangement was delayed by the transient regeneration of normal hematopoiesis and reduction of abnormal blastoid cells in the bone marrow following immunoglobulin administration. Molecular diagnosis could only be established using interphase fluorescence in situ hybridization (FISH) analysis which may be considered as a valuable additional diagnostic tool in similar cases.