title: Contribution of electron microscopy to understanding cellular differentiation in mesenchymal tumors of the gastrointestinal tract: a study of 82 tumors.
abstract: Eighty-two mesenchymal tumors of the gastrointestinal tract were examined by electron microscopy for the purposes of subtyping for diagnostic precision and of understanding cellular differentiation. Tumors were subclassified into leiomyoma/leiomyosarcoma, tumors of the interstitial cell of Cajal (equivalent to traditionally defined GISTs [Miettinen et al. Hum Pathol. 1999; 30:1213-1220; Mod Pathol. 2000; 13:1134-1142]), gastrointestinal autonomic nerve tumors (GANTs), and fibroblastic and myofibroblastic tumors, using criteria from the literature. Leiomyoma/leiomyosarcoma were diagnosed by myofilaments, attachment plaques, plasmalemmal caveolae, and lamina; GIST by processes or cell bodies full of intermediate filaments, solitary focal densities amid intermediate filaments, attachment plaques with incomplete lamina, scarce myofilaments, and smooth endoplasmic reticulum; GANTs by neuroendocrine granules, cell bodies/processes full of intermediate filaments (more rarely microtubules), and smooth endoplasmic reticulum; fibroblastic/myofibroblastic tumors by abundant rough endoplasmic reticulum, myofilaments, and fibronexuses. Seventy-three tumors (89%) were successfully subclassified, as 5 leiomyoma/leiomyosarcoma (6%), 36 GISTs (44%), 22 GANTs (27%), 10 fibroblastic and myofibroblastic tumors (12%). Results indicated overlap between poorly differentiated leiomyosarcoma and GIST, and between GIST and GANT. GANT is emphasized as a neuronal tumor identifiable by electron microscopy, and thereby distinguishable from GIST.
authors.affiliation: Department of Histopathology, Christie Hospital, Manchester, United Kingdom. brian.eyden@christie-tr.nwest.nhs.uk
authors.forename: Brian
authors.initials: B
authors.lastname: Eyden
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Chorneyko
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Shanks
authors.forename: Lia P
authors.initials: LP
authors.lastname: Menasce
authors.forename: S Sankar
authors.initials: SS
authors.lastname: Banerjee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D017776:Autonomic Pathways / Q000648:ultrastructure; D002471:Cell Transformation, Neoplastic / Q000648:ultrastructure*; D005260:Female; D005347:Fibroblasts / Q000648:ultrastructure; D005770:Gastrointestinal Neoplasms / Q000145:classification / Q000648:ultrastructure*; D006801:Humans; D007889:Leiomyoma / Q000648:ultrastructure; D007890:Leiomyosarcoma / Q000648:ultrastructure; D008297:Male; D008648:Mesoderm / Q000648:ultrastructure*; D008854:Microscopy, Electron; D008875:Middle Aged; D009197:Myenteric Plexus / Q000648:ultrastructure; D009490:Neurosecretory Systems / Q000648:ultrastructure