BACKGROUND: Internal cell biology, including apoptotic regulation, is presumed to play a key role in the development of recurrent pleomorphic adenoma (PA). AIM: The aim of our study was to determine the relevance of B-cell lymphoma 2 (bcl-2) oncoprotein immunoexpression and distribution in primary PA, and its recurrence. METHODS: Ten primary-non-recurrent, 14 primary-to-recur, and 28 recurrences of parotid PA patients aged 19-73 (mean 40.7±16.7) years were enrolled. The bcl-2 expression was compared between groups using a semi-quantitative histoscore, defined as the multiple of the percentage of cells by the intensity of immunostaining. RESULTS: Widely varying bcl-2 immunoreaction was found in the epithelial areas of 91.7% of primary and 85.2% of recurrent PA. Similarly varying but much less, immunopositivity was found in the myxoid areas of 62.5% of primary and 71.4% of recurrent tumours. No obvious differences in the bcl-2 staining intensity or pattern of specific epithelial morphologic structures in either the primary-non-recurrent, primary-to-recur or recurrent tumours were found. In both the mesenchymal and epithelial areas of PA, the differences in bcl-2 immunohistoscore between the primary-non-recurrent and primary-to-recur groups were not statistically significant (P=0.62, respectively 0.51). In the mesenchymal areas, the study revealed a significantly increased histoscore in recurrent tumours compared to their corresponding primaries (P=0.01). Increased bcl-2 expression in recurrent PA suggests an exaggerated aggressiveness of that tumor. CONCLUSION: The fact that a significant difference in the histoscore was found exclusively in the myxoid component seems to accord with the reported prevalence of the latter in recurrent and metastatic PA.

Clinic of Otorhinolaryngology and Head and Neck Surgery Central Military Hospital and Faculty Hospital Ruzomberok Slovak Republic

Clinic of Otorhinolaryngology Faculty of Medicine and Dentistry Palacky University Olomouc and University Hospital Olomouc Czech Republic

Department of Clinical and Molecular Pathology Faculty of Medicine and Dentistry Palacky University Olomouc and University Hospital Olomouc

Department of Pathology University Hospital Ostrava

Institute of Pathology Central Military Hospital and Faculty Hospital Ruzomberok Slovak Republic

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