Pseudo-Chediak-Higashi anomaly in acute myeloid leukaemia. An electron microscopical study

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 hugh inclusion, sometimes found in vacuoles, featuring fusion of lysosomes.