Edge

The edge of the ulcer provides important information about the pathophysiology of the ulcer:

• flat sloping edge: this indicates that epithelium is growing in from the ulcer edge in an attempt to heal it. Usually this edge is only seen in superficial ulcers. Often these ulcers are venous ulcers - note that the skin around the ulcer is red-blue (due to haemosiderin deposition) and almost transparent.
• punched-out (square-cut) edge: this indicates that there has been the rapid death of a whole thickness of skin without the body making much attempt to repair of the defect. This type of ulcer is often caused by pressure on an insensitive area of skin. Examples include diabetes, syphilis, any other peripheral neuropathies.
• undermined ulcer: this is seen when an infection at an ulcer site affects the subcutaneous tissues more than the skin. This occurs in tuberculosis ulcers.
• rolled edge: this occurs where there is slow growth of tissue at the ulcer edge and the peripheral tissue becomes heaped-up. This is classically seen in a rodent ulcer (basal cell carcinoma).
• everted edge: in this case the tissue at the edge of the ulcer is growing so fast that it overlaps the normal skin as it 'spills out' of the ulcer site. An everted edge is seen in carcinomata.

Reference

1. Grey JE, Harding KG, Enoch S. Venous and arterial leg ulcers. BMJ. 2006 Feb 11;332(7537):347-50.