Tubular Complexes of Endoplasmic Reticulum in Myeloblasts of Acute Myelogenous Leukemia

The leukemic cells from 9 patients with acute myelogenous leukemia were studied by light microscopy, cytochemistry, and electron microscopy. In Wright-Giemsa-stained blood and bone marrow preparations, from less than 1% to greater than 95% of the leukemic cells from the 9 patients contained inclusions that measured one-third to one-half the diameter of the cell. In 4 patients the inclusions appeared to be associated with intense focal myeloperoxidase activity. Ultrastructural studies demonstrated that the inclusions were complexes of smooth, membranous, anastomosing 50-nm tubules and 80-nm particles. These complexes were surrounded by bundles of microfilaments and numerous mitochondria. The tubular complexes resembled the tubuloreticular structures that have been reported in lymphoreticular and endothelial cells from patients with autoimmune and viral diseases.