Benign lymphocytosis and reactive neutrophilia. Laboratory features provide diagnostic clues.

Peripheral blood leukocytoses are some of the most common abnormalities observed in the clinical hematology laboratory. This article discusses both benign lymphocytosis and reactive neutrophilia. Laboratory features and clinical syndromes associated with each of these specific leukocytoses and diagnostic considerations including differentiation from malignant disorders are addressed.

Erythroleukemia: a review of 15 cases meeting 1985 FAB criteria and survey of the literature.

Erythroleukemia (EL) is a rare form of myelogenous leukemia the classification and definition of which has evolved over the course of its 80-year descriptive history. In 1976 the French American British (FAB) Cooperative Group included EL within the classification system of acute myelogenous leukemias as AML-M6, and agreed on a quantitative standard to be used in the diagnosis of this disorder. The standards were revised in 1985 to the form in use today. We selected a series of 15 cases from our records which specifically fit the FAB criteria for AML-M6. Extensive direct comparison between our series and the old literature is not practical because of the changes which have occurred in classification and definition of the disease. Overall we found a rough correlation between the clinical and laboratory data shown in the old literature on EL and data from our cases. These cases underscore characteristic laboratory features which correspond to what is now defined as AML-M6: these patients present with pancytopenia, frequent peripheral blood nRBCs and no, or few, peripheral blood blasts. In addition, we note the presence of a hybrid myeloid-erythroid blast in the bone marrow in this disease and suggest that this may be characteristic of this type of AML. Old literature on EL has generally shown it to be a disease of the elderly, yet we found a subset of younger patients whose clinical outcome was significantly better than that of the older patients. Finally, EL has historically been viewed as a disease in which patients progress from a prodrome through erythroleukemia to other acute myeloid leukemia (AML) subtypes. Consistent with this idea, half of our 15 patients had been previously diagnosed with myelodysplastic syndrome or received chemotherapy. On the other hand only one of the 15 patients converted to another type of AML during his course.

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.

Carbonic anhydrase: a marker for the erythroid phenotype in acute nonlymphocytic leukemia.

Protein markers are often used to corroborate the morphological subtyping of hematopoietic malignancy. Most commonly, surface markers are used for the phenotyping of hematopoietic cells; however, internal proteins have also been used as markers. Glycophorin, hemoglobin A, hemoglobin F, and transferrin have all been used as markers for the erythroid phenotype. We have recently shown that carbonic anhydrase is constitutively and aberrantly expressed in two erythroleukemic cell lines. We here show that it is also present in high levels in primary erythroleukemic blasts and that it is a useful marker for the M6 phenotype when classifying acute nonlymphocytic leukemia.

Melanin inclusions in the peripheral blood leukocytes of a patient with malignant melanoma.

Dark pigmented inclusions were found in the monocytes and polymorphonuclear leukocytes of a patient with widely metastatic malignant melanoma. Special stains demonstrated the granules were composed of melanin. The authors are not aware of any previous case report of patients with metastatic malignant melanoma that had leukocytic melanin inclusions. Prospective search for this phenomenon in malignant melanoma patients may allow such a finding to be used as a diagnostic tool.