The presence of Merkel cells and CD10‐ and CD34‐positive stromal cells compared in benign and malignant oral tumors

Background: To describe sequential changes in Merkel cells (MC), and CD10⁺ and CD34⁺ stromal cells (SC) during the transition from benign to malignant oral lesions and correlate with clinicopathologic parameters. Materials and methods: Changes in cytokeratin 20‐positive (CK20⁺) Merkel cells, CD10⁺ and CD34⁺ SC were immunohistochemically examined in specimens of 28 oral verrucous carcinomas (VC), 32 squamous cell carcinomas (SCC) and 36 benign squamous lesions (BSL). Immunoreactivity and localized inflammation were measured quantitatively and/or semiquantitatively, and between‐group results were statistically compared. Results: The mean number of CD34⁺ SC was significantly lower in VC (57.36) and SCC (33.81) than BSL (351.56, P < 0.001). However, the three tumor types had similar staining level and number of CD10⁺ SC. We found a significant difference in the density of MC between BSL and VC (P < 0.001) or SCC (P < 0.001). The number of CK20⁺ MC was significantly lower in highly inflamed specimens than mildly inflamed specimens (P = 0.001). Conclusion: CD34⁺ SC and to a lesser extent MC, but not CD10⁺ SC, reveal statistically different density during the transition from benign to malignant oral lesions. The correlations between the CD34⁺ SC expression and squamous lesions may be associated with epithelial dysplasia and/or tumor invasion.