Four cases having acute myelomonocytic leukemia with bone marrow eosinophilia (M4E0) are reported.
Chromosomal analyses revealed an inversion of chromosome 16, inv (16) (p13q22), in all bone marrow cells examined. Cytologic study showed an increased percentage of eosinophils in the bone marrow with several abnormalities such as nuclear hyposegmentation, a mixture of eosinophilic and basophilic staining granules in the cytoplasm, and positivity of their granules to naphthol AS-D chloroacetate esterase and periodic acid-Schiff reactions. As inv (16) is observed in metaphases of eosinophilis, it is suggested that marrow eosinophils of M4E0 are part of the neoplastic process.
Eighty-two out of 93 (88%) patients with M4E0 in the literature, including our 4 cases, entered complete remission after treatment. It is likely that M4E0 is sensitive to chemotherapy. However, we suggest that much longer follow-up should be conducted to investigate for long-term survival based on the data of patients in the literature.
