Erythroplakia is considered the oral lesion with the highest risk of malignant transformation due to its association with severe epithelial dysplasia, carcinoma in situ, or invasive carcinoma upon biopsy. Clinically, it appears as a well-demarcated red patch that lacks the keratinization seen in leukoplakia, indicating more profound mucosal alteration. The vascularity and epithelial atrophy contribute to its red appearance and correlate with greater cellular atypia. Early surgical excision and close follow-up are critical because erythroplakia often represents a precursor to squamous cell carcinoma. In contrast, other lesions like leukoplakia have a lower and more variable risk of malignant change.

Reference: Oral Pathology, Neville et al., 4th Edition.