38
Views
88
CrossRef citations to date
0
Altmetric
Original Article

Subclassification of Gastrointestinal Stromal Tumors Based on Evaluation by Electron Microscopy and Immunohistochemistry

, &
Pages 373-393 | Published online: 10 Jul 2009
 

Abstract

Fifty-six gastrointestinal stromal tumors (GIST) were subclassified by ultrastructural examination and by immunophenotypic analysis using a panel of 13 antibodies. Eighty percent of the tumors originated in the stomach and small intestines. The neoplasms were classified as follows: 42.9% smooth muscle tumors (4 leiomyomas, 9 spindle cell and 8 epithelioid leiomyosarcomas, and 3 mixed spindle cell and epithelioid leiomyosarcomas); 37.5% gastrointestinal autonomic nerve tumors (GANT), 47.6% of which arose in the small intestines; 8.9% mixed leiomyosarcoma/neurogenic tumors; and 10.7% undifferentiated GIST, not otherwise specified. The muscle common actin antibody HHF-35, variably reactive with tumor cells composing 23 of 24 smooth muscle tumors, was found to be the most sensitive marker of leiomyocyte differentiation. One immunophenotypically questionable spindle cell leiomyosarcoma was diagnosed by electron microscopy. Since neuron specific enolase positive cells were found in 1/3 of the leiomyosarcoma cases, the ultrastructural demonstration of synapse-like structures and neurosecretory granules was required for diagnosing GANTs. The immunophenotype of the ultra-structurally undifferentiated GIST was vimentin and CD34 +. Variable numbers of ultrastructurally undifferentiated cells also were found in all of the tumors except 2 leiomyomas. CD34 was also expressed in smooth muscle (54%) and GAN (62%) tumors. Despite their similar light microscopic appearance, GIST are phenotypically heterogeneous, requiring both ultrastructural and immunohistochemical studies for accurate characterization.

Reprints and Corporate Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

To request a reprint or corporate permissions for this article, please click on the relevant link below:

Academic Permissions

Please note: Selecting permissions does not provide access to the full text of the article, please see our help page How do I view content?

Obtain permissions instantly via Rightslink by clicking on the button below:

If you are unable to obtain permissions via Rightslink, please complete and submit this Permissions form. For more information, please visit our Permissions help page.