title: Ultrastructural characteristics and lysozyme content in hypergranular and variant type of acute promyelocytic leukaemia.
abstract: We investigated the electronmicroscopic (EM) features and cellular lysozyme (LZ) content in 16 cases of acute promyelocytic leukaemia (APL): 11 cases of the hypergranular form (M3) and five cases of the microgranular variant (M3-V). The main EM features in all cases were: irregular, folded or bilobed nuclei, many cytoplasmic granules, distended rough endoplasmic reticulum (RER) cisternae which, in some cases, presented as stellate forms (more frequent in M3-V), and bundles of cytoplasmic microfilaments. Many Auer rods were present in M3 cases and few in M3-V; most of these disclosed parallel tubular arrays (PTA) with a varied periodicity ranging from 13 to 26 nm. There was a significant difference between M3 and M3-V (P<0.0001) in both the number of granules per cell section (62.9 +/- 34.5 v 38.0 +/- 23.6) and in the granule section area (0.044 +/- 0.033 v 0.026 +/- 0.015 microm2). In some cases, mainly in M3-V, we found cells with large granules containing PTA which probably represent poorly developed Auer rods. Intracellular LZ content assayed by a post-embedding immunogold method, showed high granular LZ density (in the range of that found in M4 and M5) in M3 cells and very low granular LZ content in M3-V. This study adds new objective parameters for the diagnosis of these two types of APL and provides new information on their LZ pattern of expression.
authors.affiliation: Efrati Research Institute for Blood Cells and Cytology, Rehovot, Israel.
authors.forename: D
authors.initials: D
authors.lastname: Shaft
authors.forename: M
authors.initials: M
authors.lastname: Shtalrid
authors.forename: A
authors.initials: A
authors.lastname: Berebi
authors.forename: D
authors.initials: D
authors.lastname: Catovsky
authors.forename: P
authors.initials: P
authors.lastname: Resnitzky
mesh_terms: D018870:Endoplasmic Reticulum, Rough / Q000648:ultrastructure; D006098:Granulocytes / Q000648:ultrastructure*; D006801:Humans; D007150:Immunohistochemistry; D015473:Leukemia, Promyelocytic, Acute / Q000473:pathology*; D008854:Microscopy, Electron; D009113:Muramidase / Q000737:chemistry / Q000648:ultrastructure*
chemical_list: D009113:Muramidase