Which of the following lesions cannot be classified as an intra-epithelial lesion?

The classification of intra-epithelial lesions pertains to alterations or abnormalities that occur within the epithelial layer of tissues, particularly in the oral cavity. In this context, lichen planus is considered a mucocutaneous disease that primarily affects the epithelium but does not fall under the classification of intra-epithelial lesions in the same way as other options.

Lichen planus presents with distinctive clinical features, such as white striations or plaques and is categorized more as a lichenoid reaction or condition that impacts the entire epithelium rather than creating specific intra-epithelial lesions. This differs from conditions like pemphigus vulgaris, which qualifies as an intra-epithelial lesion, as it directly involves autoimmune mechanisms that disrupt the connections between epithelial cells, leading to blister formation within the epithelium itself.

Herpes simplex infections and hand, foot, and mouth disease also demonstrate characteristics of intra-epithelial lesions due to their viral nature, which leads to direct involvement and disease processes within the epithelium. These lesions are typically associated with more localized pathology within the epithelial strata, which distinguishes them from what is seen in lichen planus.