Pleomorphic adenoma and carcinoma ex pleomorphic adenoma: immunohistochemical demonstration of the association between tenascin expression and malignancy.
OBJECTIVE
To investigate tenascin expression in salivary gland tumours. Tenascin is a matricellular protein that has been studied in several tumour types. Its expression has been correlated with tumour morphogenesis as well as with local invasiveness and tumour metastatic behaviour.


RESULTS
The distribution pattern of tenascin in a series of 63 pleomorphic adenomas (PA) and 20 carcinomas ex- pleomorphic adenoma (Ca ex PA) was studied immunohistochemically. Ten normal adult salivary glands were used as controls. Tenascin surrounded the excretory ducts of normal adult salivary gland tissue. It was absent in the basement membrane compartment of both benign and malignant mixed tumours. In the interstitial compartment of the extracellular matrix, the fibro-hyaline type expressed tenascin in a statistically significantly (P < 0.001) lower number of PA cases (25%) in comparison with both malignant and benign areas of Ca ex PA (75% and 90%, respectively). In the Ca ex PA group, a statistically significantly difference (P < 0.001) was found in the frequency of tenascin deposits around aggregates of neoplastic cells between metastasizing (73%) and non-metastasizing neoplasms (0%).


CONCLUSIONS
These findings strongly support the hypothesis that tenascin deposition is involved in the mechanisms of malignant transformation of pleomorphic adenomas into carcinomas as well as being associated with clinical disease progression.
Serviço de Anatomia Patológica, Instituto Português de Oncologia de Francisco Gentil, Lisboa, Portugal. afelix@ipolisboa.min-saude.pt
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Félix
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Rosa
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Fonseca
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Cidadão
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Soares
D000230:Adenocarcinoma / Q000378:metabolism / Q000556:secondary*; D008949:Adenoma, Pleomorphic / Q000378:metabolism / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000378:metabolism / Q000473:pathology*; D012468:Salivary Gland Neoplasms / Q000378:metabolism / Q000473:pathology*; D019063:Tenascin / Q000378:metabolism*
D014408:Biomarkers, Tumor; D019063:Tenascin