ORIGINAL ARTICLE

Maspin expression in carcinoma ex pleomorphic adenoma

M T Martins¹, A Altemani², L Freitas² and V C Araújo³

¹ Department of Oral Pathology, School of Dentistry, University of São Paulo, 05508-900, São Paulo, SP, Brazil
² Department of Pathology, School of Medicine, University of Campinas, 13083-970 Campinas, SP, Brazil
³ São Leopoldo Mandic Centre, 13041-445 Campinas, SP, Brazil

Correspondence to:
Correspondence to:
Dr M T Martins
Department of Oral Pathology, School of Dentistry, University of São Paulo, Avenue Prof. Lineu Prestes, 2227, 05508-900, São Paulo, SP, Brazil; mariliam{at}usp.br

Aims: To investigate the presence and distribution of the protein maspin in carcinoma ex pleomorphic adenoma (CXPA).

Methods: Maspin expression was studied by means of immunohistochemistry in 16 cases of CXPA, using the labelled polymer method.

Results: According to the extent of invasion, the tumours were subdivided into: intracapsular (five cases), minimally invasive (four cases), and invasive (seven cases). Twelve patients had carcinoma with only epithelial differentiation, whereas four had a malignant myoepithelial component. Non-luminal cells in the duct-like structures of the remnant pleomorphic adenoma were strongly positive for maspin, whereas only a few luminal cells were immunopositive. A few positive cells were seen in the frequent hypocellular and hyalinised areas. Maspin was abundantly expressed, mainly in non-luminal cells, in transitional areas of CXPA with only epithelial differentiation. In frankly carcinomatous areas there was a gradual decrease in maspin expression. Almost all cells were maspin positive in CXPA with a myoepithelial component. When present, luminal cells were in general negative for maspin.

Conclusions: When only epithelial cells undergo malignant transformation, maspin expression is gradually lost. In cases with a myoepithelial component, maspin expression is high, and this might be related to the tumour suppressor activity attributed to this cell.

Abbreviations: CXPA, carcinoma ex pleomorphic adenoma; PA, pleomorphic adenoma

Keywords: carcinoma ex pleomorphic adenoma; maspin; myoepithelial cell; immunohistochemistry

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