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Simple mucin-type carbohydrate antigens in pleomorphic adenomas
M H Therkildsen1, U Mandel, M Christensen
1Department of Pathology, Rigshospitalet, University of Copenhagen, Denmark.
Summary
Simple mucin-type carbohydrate structures like Tn and sialosyl-Tn are aberrantly expressed in pleomorphic adenomas, unlike normal salivary glands. T antigen may serve as a marker for myoepithelial cells in these tumors.
Area of Science:
- Oncology
- Glycobiology
- Pathology
Background:
- Simple mucin-type carbohydrate structures (T, Tn, sialosyl-Tn) are general carcinoma markers due to precursor accumulation.
- These structures are rarely found in normal tissues and secretions, including salivary glands.
Purpose of the Study:
- To investigate the expression of simple mucin-type carbohydrate structures and ABH(O) variants in pleomorphic adenomas.
- To determine if these structures can serve as diagnostic markers in salivary gland tumors.
Main Methods:
- Immunohistology was used on paraffin-embedded and frozen tissue sections from 37 pleomorphic adenomas and normal parotid tissue.
- A panel of monoclonal antibodies (MAbs) specific for T, Tn, sialosyl-Tn, and blood group H and A variants was employed.
Main Results:
- Immature Tn and sialosyl-Tn antigens were expressed in tumor epithelial ductular structures but absent in normal parotid tissue, indicating aberrant glycosylation.
- Pleomorphic adenomas showed a loss of A antigen expression.
- Modified myoepithelial cells (MECs) expressed T and sialosyl-T antigens, similar to normal MECs and basal cells.
Conclusions:
- Aberrant glycosylation with precursor accumulation occurs in pleomorphic adenomas.
- T antigen expression in modified MECs suggests it could be a marker for myoepithelial differentiation in salivary gland tumors.