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Two cases of myeloproliferative disorder--one of myelofibrosis with agnogenic myeloid metaplasia and one of chronic granulocytic leukaemia terminating in acute micromegakaryoblastic leukaemia--are presented. The clinical course is described, and results are reported of morphological, cytometric, cytochemical and cytogenetic studies, as well as cell culture of blood cells in soft agar and in fluid medium.

2 cases of acute myeloid leukaemia with inclusion bodies are presented. The inclusions were found mainly in the blast cells but could also be encountered in lymphocytes and plasma cells. Cytochemical and ultrastructural studies showed a great resemblance of these inclusions to the ones found in Chediak-Higashi anomaly, i.e., high acid phosphatase activity, varying in size of inclusions from clusters of small granules to huge inclusion, sometimes found in vacuoles, featuring fusion of lysosomes.

Peripheral blood and bone marrow cells from three children with the juvenile (Ph1 negative) type of chronic granulocytic leukemia and from one with the adult (Ph1 positive) type were cultured in soft agar, and their specific growth patterns were evaluated. Greatly increased numbers of colonies were obtained in all cases, particularly from peripheral blood cells. By morphologic, cytochemical and ultrastructural criteria, colonies from one juvenile type and from the single adult type patients were found to be almost exclusively granulocytic, whereas in the other two juvenile type leukemia patients colonies were either granulocytic or macrophage. Moreover, both growth patterns were obtained in the same patients on different occasions. It appears that the leukemic cell populations of the juvenile and the adult forms of chronic granulocytic leukemia do not arise from different cell lines. Rather, both are the progeny of the common monocyte-granulocyte progenitor cell, whose abnormal proliferation and differentiation along either the granulocytic or the monocytic pathway is probably directed by fluctuations in humoral and/or microenvironmental factors.