The following two figures demonstrate the different structures and layers that form the lip.

Clinical case

A 30-year-old beautifully tanned model visits her plastic surgeon because of a small ulcer she has had on the outer edge of her lower lip for the past 6 months. The ulcer is found to be shallow and has hard, everted edges. The patient says that the ulcer is painless but is worrying her because it is gradually increasing in size. Excision biopsy reveals that the ulcer is malignant. Using your knowledge of histology, describe the surface epithelium of the lip. Explain why the margins of the lips are red. Why are the lips of some patients sometimes blue?

Microscopy

This is a low magnification of a section through the inner surface of the lip to demonstrate the labial glands and epithelia. Fig 51-001

This is a low magnification of a section through the outer surface of the lip demonstrating the skin. Fig 51-002

Memorandum
Clinical case	Fig 51-001	Fig 51-002