A 37-year-old male patient was admitted with chief complaints of fever and hemorrhagic diathesis. Physical examination showed anemia, gingiva swelling, generalized lymphadenopathy and hepatosplenomegaly. Blood examination revealed marked anemia and thrombocytopenia. The leukocyte count was 22,700/μl with 28.5% blasts, 56.0% monocytoid cells and 1.0% eosinophils. Bone marrow study revealed hypercellularity with 39.6% blasts, 10.8% promyelocytes, 12.4% promonocytes and monocytoid cells, and 23.6% eosinophils in various maturational stages.
The morphology of the eosinophils was atypical in respect of large cell-size, vacuolated cytoplasma, large azurophilic-basophilic granules and asynchronous nuclear-cytoplasmic maturation. Cytochemically, thirty percentage of blasts were peroxidase positive, 40% of blasts were positive for acetate esterase and/or chloroacetate esterase. Eosinophils were positive for chloroacetate esterase, suggestive of leukemic nature. Levels of serum and urine lysozyme were elevated.
Chromosomal analyses of bone marrow cells were normal. Electron microscopic study revealed the absence of crystalloid internum in specific granules of eosinophils.
A diagnosis of acute eosinophilo-myelomonocytic leukemia was made. Induction chemotherapy with three courses of DCVP (daunorubicin, cytosine arabinoside, vincristine, and prednisolone) resulted in complete remission. One year later, bone marrow showed the similar finding to that of onset. The reinduction chemotherapy gave no remission, and he died of pneumonia 15 months after the diagnosis.
At autopsy, leukemic cells were found to infiltrate in bone marrow, liver (2,110 g), spleen (490 g), lung, and kidney etc, although no evidences of reactive eosinophilia such as collagen disease, endocarditis, or parasitic disease were seen.
Acute eosinophilo-myelomonocytic leukemia seems to be classified as a rare type of M4 variant in the FAB classification.
