METHODS: Tissues from 62 salivary gland tumours were assembled in tissue microarray format. There were 13 adenoid cystic carcinomas (ACC), 10 carcinoma ex pleomorphic adenomas (CEPA), 10 mucoepidermoid carcinomas (MEC), 10 polymorphous low-grade adenocarcinomas (PLGA), 10 pleomorphic adenomas (PA) and 9 acinic cell carcinomas (AcCC). Clinicopathological data were collected retrospectively and immunohistochemical analyses of Mcm-2, Ki-67 and geminin were performed on all lesions. Labelling index (LI) for each marker was determined by counting the percentage of positive cells in 6 random fields from 3 arrays per case.
RESULTS: Mcm-2 expression was higher than Ki-67 and geminin in all tumours studied. Mcm-2 LI was higher (ANOVA, p<0.05) in ACC (28.2% ± 19.2) than in all other tumours including PLGA (5.3% ± 4.1) and PA (6.9% ± 5.0). Mcm-2 LI was higher in CEPA (20.4% ± 5.0) than in PA. LI did not correlate to tumour grade or outcome for any of the markers or tumour types.
CONCLUSIONS: The findings suggest that Mcm-2 may be a sensitive proliferation marker in salivary gland tumours and may be useful for differential diagnosis between PA and CEPA and ACC and PLGA. Further studies are warranted to assess the value of Mcm-2 as a predictor of recurrence and survival.
Supported by: CNPq (The National Council for Scientific and Technological Development –Brazil- 200291/2006-8).