A case of juvenile myelomonocytic leukemia with concomitant cytomegalovirus infection.

Infantile cytomegalovirus (CMV)-associated disease and juvenile myelomonocytic leukemia (JMML) frequently present with similar clinical features, and thus the differential diagnosis is often difficult. An early and definite diagnosis of these disorders is required because their therapeutic approaches are very different. The authors describe a 2-month-old Japanese girl with JMML and CMV infection. The CMV antigen was detected by immunologic staining of leukocytes using the peroxidase-labeled monoclonal antibody HRP-C7. To assess clonality, the X-chromosome inactivation pattern was evaluated using polymerase chain reaction analysis of the human androgen receptor gene with or without predigestion of chromosomal DNA with HhaI or HpaII. The patient showed evidence of monoclonal origin of mononuclear cells at diagnosis. Although CMV infection mimicking JMML has previously been reported in two patients, to the authors' knowledge this is the first report describing a firm and definitive diagnosis of JMML based on the study of X-chromosome inactivation patterns.