A new chromosome anomaly in acute lymphoblastic leukemia (ALL) is reported. Three, possibly four, patients showed an identical karyotype anomaly, characterized by a (4;11)(q13;q22) reciprocal translocation. This anomaly has not so far been found in lymphoproliferative disorders other than ALL. Two of the patients had congenital leukemia, but the anomaly described appears to be more characteristic of ALL than of congenital leukemia, and may help the clinician in establishing the diagnosis of ALL.

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Two patients with presumably benzene-induced malignant blood disorders with preleukemic phases were cytogenetically monitored through the courses of their diseases. Patient 1, in addition to a familial chromosome translocation [t(3;16)], developed karyotypic abnormalities in 100% of the marrow cells, including two translocation: t(9;16)] and t(4;15). Monosomy of chromosome 7 characterized the cells of patient 2. Cytogenetic monitoring of the patients at various phases of their diseases served as an important indicator of the transformation or progression of the preleukemia into frank leukemia and of the unusual behavior of such leukemic cells.

A patient with blastic crisis of chronic myelogenous leukemia (CML) is presented. The acute phase was localized in the lymph nodes and bones, causing severe osteolytic lesions and hypercalcemia. The blast cells were undifferentiated in light microscopy and by histochemical stains. As viewed under electron microscopy, a considerable proportion of the blast cells were of myeloid origin, while immunologic markers and cytogenetics indicated a lymphoid origin. It seems plausible that the patient had a mixed myeloid‐lymphoid blast crisis, but that the lymphoid blasts were responsible for the severe osteolytic lesions and the hypercalcemia.

Summary. .‘Gaucher‐like cells’ were observed in the bone marrow of 18 out of 20 HEMPAS (CDA II) patients. These cells contain birefringent, PAS positive material. Further cytochemical procedures identified the inclusions as a glycoprotein or a glycopeptide but the presence of cerebrosides could not be excluded. An intralysosomal localization was suggested by electronmicroscopy.HEMPAS is characterized by inefficient erythropoiesis and it is suggested that accumulation of a catabolite of the erythroblasts gives rise to these cells. A possible relation with the cell membrane anomaly of HEMPAS erythrocytes is discussed.