Figure 1

This representative mucosal biopsy of the oral cavity shows regular squamous epithelium (Figure 1 left side) and a high-grade epithelial dysplasia. In comparison, the dysplasia on the right hand side of the picture shows a loss of maturation and nuclear atypia, like high nuclear-to-cytoplasmic ratio and nuclear irregularity, involving the whole squamous cell layer of the mucosa. Invasive tumour growth was not found.