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A patient with Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia (CML) entered a blast crisis localized to lymph nodes. On light microscopy, by morphology and histochemical staining, the blasts were undifferentiated. In spite of terminal deoxynucleotidyl transferase positivity, some of the lymph node cells expressed a myeloid differentiation antigen, OKM1, and were peroxidase positive by transmission electron microscopy (TEM). However, the majority of cells were peroxidase negative on TEM and expressed OKT-10, a marker found on both primitive myeloid and lymphoid cells. Cultures of lymph node cells stimulated with Epstein-Barr virus or lipopolysaccharide (LPS) revealed the Ph1, indicating B cell involvement in the CML. T cells from cultures stimulated with L4-phytohemagglutinin and T cell growth factor were negative for the Ph1. In unstimulated lymph node cells, the uncomplicated Ph1 could not be demonstrated; instead, a unique complex karyotype involving a masked Ph1 was identified in these and the LPS cultures. This karyotype was not found in bone marrow (BM) metaphase cells. Instead, BM cells showed either the simple Ph1 or the Ph1 with a rearrangement involving chromosomes 13 and 20. The patient had transient responses to three chemotherapy regimens, two of which were designed to treat acute lymphocytic leukemia, but he died 8 months after disease acceleration without BM blast crisis. These findings are compatible with an extramedullary blast crisis originating in a primitive cell with both myeloid and lymphoid characteristics.

Unusual cytogenetic findings are described in two patients with acute leukemia and rearrangements involving chromosomes 4 and 11. Both patients had clinical and phenotypic features often found in leukemia with t(4;11)(q21;q23). At initial diagnosis, one patient showed a standard t(4;11) with duplication of the 4q-translocation derivative. The latter finding has been described previously in a few patients with t(4;11) in association with disease progression. By analogy with the Ph1 chromosome in chronic myelogenous leukemia, duplication of the 4q-suggests that this derivative is the critical recombinant in the t(4;11). The second patient has a novel complex translocation, t(4;11;15)(q21;q23;q21). Analysis of this variant trans-location implies that the 11 q + is the consistent chromosome rearrangement in this type of leukemia. The apparent contradiction of the findings in these and other relevant reported cases reviewed here suggests that genes on both the 11q+ and 4q-recombinant chromosomes are important, in either the etiology or the progression of this disease.

Six patients with M4 acute myelomonocytic leukemia ( AMMoL ) were identified who had abnormalities of chromosome 16 in bone marrow cells. Five had a pericentric inversion, inv(16)( p13q22 ), and a sixth patient had a translocation, t(16;16)(p13.1;q22). Each of these six patients had bone marrow eosinophils that were abnormal in morphology on light and/or electron microscopy and by cytochemical stains. The eosinophils constituted 1%-24% of nucleated marrow cells. Of 61 acute nonlymphocytic leukemia (ANLL) patients, all those with AMMoL and abnormal bone marrow eosinophils had an inv(16) or a t(16;16). One other patient in this group had a rearrangement of chromosome 16 (with a break in the short arm at band p13); however, the ANLL type was M1 and no abnormal eosinophils were present. Four patients with ANLL types other than M4 had an increase in marrow eosinophils; three in whom the eosinophils appeared normal and one with ANLL-M2 and bizarre eosinophils morphologically distinct from those seen in AMMoL . Chromosome pair 16 was normal in the latter four patients. AMMoL with dysplastic bone marrow eosinophils appears to represent a unique clinicopathologic entity associated with several related abnormalities affecting 16q . The morphologic features of both blasts and eosinophils may be more important than the absolute number of eosinophils in the marrow in identifying this group of patients. This may have prognostic importance as five of six patients achieved complete remission with standard antileukemic therapy and are still alive.

Ten of 136 consecutive adult patients with previously untreated acute leukemia had morphologically undifferentiated leukemia by light microscopy. Leukemic cells from these patients were characterized by agranular cytoplasm, negative histochemical staining with sudan black (SB) and nonspecific esterase, and absent lymphoid cell surface markers and therefore were not classifiable according to the French-American- British (FAB) system. Electron microscopy with myeloperoxidase (MPO) staining revealed the presence of peroxidase positive cytoplasmic granules and endoplasmic reticulum in eight of the nine patients studied. Cells from the patient who was negative for MPO were also negative for platelet peroxidase. A series of monoclonal antibodies to myeloid antigens also revealed myeloid features with all patients having at least one myeloid differentiation antigen present on the surface of their cells. Common acute lymphoblastic leukemia (ALL) antigen was absent in the nine patients tested. Cytogenetic analysis of blast cells was abnormal in seven patients on whom adequately banded chromosomes were obtained although there were no consistent abnormalities. No patient had a Ph1 chromosome. Only two of the ten patients achieved a complete remission. Morphologically undifferentiated leukemia may have myeloid features when studied by transmission electron microscopy or with monoclonal antibodies for cell surface markers. Such studies should be performed when the leukemia cannot be classified using either light microscopy or lymphoid cell surface markers. Such patients infrequently achieve remission with standard therapy and constitute a distinct entity.

Eosinophils derived from HL-60 cells share many of the abnormalities of granule histochemistry and morphology frequently seen in eosinophils of patients with certain malignancies, especially those seen in acute myelomonocytic leukemia with abnormal eosinophils (FAB class M4eo). In order to understand the pathogenesis of these abnormalities, four enzymes, characteristic of the eosinophil, were studied in HL-60 promyelocytic leukemia cells at various stages of eosinophilic differentiation. Using biochemical and ultrahistochemical techniques, the following differences from normal eosinophil development were demonstrated. First, both myeloperoxidase and eosinophil peroxidase coexisted in the population of maturing HL-60 eosinophils. Second, the granules formed from the condensation of material in vacuoles which were derived from dilated segments of the endoplasmic reticulum; the role of the Golgi apparatus in processing of peroxidase appeared minimal. Third, low levels of lysophospholipase and arylsulfatase were present in the cells compared to normal eosinophils. Finally, crystallizations resembling precursor structures of Auer rods appeared in the granules of about 5% of the cells. These findings suggest that several disorders of the control of protein synthesis and processing exist in HL-60 eosinophils which may be responsible for the abnormal granule morphology and histochemistry.

Near-tetraploid clones were observed in bone marrow (BM) samples from two patients with acute leukemia. One case had a hypotetraploid clone (model chromosome range, 88–90) characterized by two apparently identical 8:21 translocations and loss of both Y chromosomes as well as by other changes. As in aneuploid patients with only a single 8:21 translocation, the cytologic features in this case were characteristic of acute myeloid leukemia with maturation. The marrow of the second patient contained immature leukemic blasts indicative of acute myeloid leukemia. The abnormal clone in this patient contained 93 chromosomes with an extra small marker. In this case we examined BM preparations that were made by several different cytogenetic methods: “direct” and 24-hr culture (with or without methotrexate synchronization). We scanned 100 consecutive mitotic cells from each of the three preparations and found almost no variation in the incidence of abnormal metaphase cells. However, in this particular case, we noted some disparity between preparations with respect to the quality of diploid mitoses versus that of near-tetraploid mitoses. This finding is discussed with near-tetraploid mitoses. This finding is discussed with regard to bias in selecting metaphase cells for banding analysis in acute leukemia in general. In both of our patients there was a close correlation between the incidence of polyploid mitoses observed in cytogenetic preparations and the incidence of bizarre blast cells found in BM smears on the same date.