Inflammatory Infliltrate in Oral Epithelial Dysplasia and Squamous Cell Carcinoma

Inflammatory cell infiltrate is routinely associated with epithelial dysplasia and established SCC of the oral mucosa. Changes in infiltrates during progression from dysplasia to invasive carcinoma have not been reported. Objective: Compare oral epithelial dysplasia with SCC for associated leukocytes, including B lymphocytes and monocytes/macrophages. Methods: A) Specimens: Serial 5um sections of archival formalin-fixed, paraffin-embedded tissue blocks from the College of Dentistry Oral Pathology Laboratory, diagnosed as focal keratosis with/without mild dysplasia (Group 1, 19 cases), moderate/severe dysplasia (Group 2, 13 cases), and SCC (Group 3, 18 cases). B) Immunohistochemistry: Adjacent sections were stained with monoclonal antibodies for leukocyte common antigen (CD45, LCA; Biogenex, San Ramon, CA), B lymphocytes (CD20; Biogenex), monocytes/macrophages (CD68; Labvision, Fremont, CA), or negative control (MIgG; Biogenex), followed by HRP – DAB Detection kit (Labvision). C) Analysis: Inflammatory infiltrate in lamina propria was analyzed for character (diffuse or localized), numbers and co-localization of CD20+ and CD68+ cells in multiple high-power fields (HPF). Results: While inflammation was diffuse in most cases in all groups, Group 1 (79%,), Group 2 (92%), and Group 3 (94%), large lymphoid aggregates were more common in Group 3 (38%), vs 10% in Group 1 and 0% in Group 2. Number of cases per group with high B cell presence (>10/HPF) increased from 32% in Group1, to 62% in Group 2, to 78% in Group 3, but little change was seen in macrophages (42%, 46% and 47%, respectively). Conclusion: Diffuse inflammation is common subjacent to dysplastic oral epithelium and oral SCC. B lymphocyte infiltration increases significantly with progression from mild dysplasia to invasive squamous cell carcinoma, while presence of monocytes/macrophages remains relatively stable. Increase in B cells with cancer progression may suggest skewing of the immune response towards antibody-mediated type. Supported by NIH/NIDCR P30 DE10226 and by the UI Dental Research Award.