A hybrid eosinophilic-basophilic granulocyte in chronic granulocytic leukemia

Morphologic observation of the peripheral blood smear from a patient with chronic granulocytic leukemia suggested the presence of eosinophilic and basophilic granules in the same individual granulocyte. To unambiguously identify eosinophilic and basophilic granules simultaneously in the same preparation, the authors developed a cytochemical staining procedure using basophil-specific toluidine blue and eosinophil-specific cyanide-resistant peroxidase. Using this new dual stain, they demonstrated that ten out of ten chronic granulocytic leukemia patients they examined had cells that contained both eosinophilic and basophilic granules. The identity of the granules was corroborated by electron microscopic studies. These observations suggest that lineage confusion is common in chronic granulocytic leukemia.