An ulcer is defined as an area of discontinuity of the surface epithelium and may occur internally (mucosal) or externally, when it involves the skin, subcutaneous tissues. Ulceration has a varied aetiology and ulcers may be benign or malignant in nature. In establishing the nature of an ulcer, certain characteristics are important, including the site of the ulcer, its floor, and its base and edges. The history is also important and often provides useful diagnostic clues. The duration of the ulcer, history of trauma and the presence or absence of pain are all relevant.
Floor of an ulcer
The floor of an ulcer is made up of fibrovascular granulation tissue. If this consists of healthy pink granulations, the ulcer has an excellent chance of healing. By contrast, healing is compromised if the floor is covered by grey slough and pale granulation tissue, e.g. neuropathic or trophic ulcers. These are deep penetrating ulcers found on pressure areas of the feet in patients with absent or diminished sensation due to peripheral neuropathy from any cause (often diabetes). They are characteristically painless because of the anaesthesia involved in their aetiology, since they are attributable in part to repeated unrecognized trauma. Ischaemic ulcers have virtually no granulation tissue and may expose underlying structures such as tendons, muscles and periosteum. They usually require limb revascularization (by arterial surgery to restore blood flow to the limb) and sometimes skin grafting.
Base of an ulcer
The base refers to the state of the tissues underneath and around the floor of the ulcer. If there is inflammatory involvement, the surrounding tissues feel indurated and the ulcer appears fixed and is tender. Fixation and induration may be the result of neoplastic infiltration of the deeper tissues if the ulcer is malignant. In this instance, fixation is not accompanied by tenderness.
Edge of an ulcer
The edge is often indicative of the nature of the lesion.
- Sloping blue edges indicate advancing epithelium (over the red granulation tissue) and signify healing. Blue healing edges are often encountered in venous (gravitational) ulcers.
- Punched-out ulcers with sharp edges used to be characteristic of syphilis in the days before antibiotics. These have virtually disappeared from clinical practice nowadays and a more typical example of a punched-out ulcer is the neuropathic ulcer due to peripheral neuropathy, most commonly encountered in diabetic patients.
- Undermined edges are typical of decubitus ulcers (pressure sores) and tuberculous ulcers which, though rare in the West, are still common in developing countries. Decubitus ulcers are the result of poor medical and nursing care of patients confined to bed for prolonged periods as a result of illness or operation. These ulcers are caused by compression necrosis of the skin and subcutaneous tissues over pressure points: heels, sacral region, scapular region. Decubitus ulcers are largely preventable by ensuring clean soft bedding and frequent turning of these immobile patients.
- Rolled or everted edges are seen when central ulceration is accompanied by growth at the edges and are characteristic of malignant ulcers such as basal cell carcinoma, squamous cell carcinoma of the skin. Eversion of the edges is more prominent in squamous carcinomas than in basal cell lesions, where the edges are gently rolled and the floor is often encrusted.
Site of an ulcer
The site of an ulcer may be a clue to the diagnosis. Examples of this include the predilection of basal cell lesions for the upper third of the face and forehead, occurrence of venous ulcers around the medial malleolus, frequency of ischaemic ulcers on the anterior aspect of the shin and dorsum of the foot, location of trophic ulcers on the sole of the forefoot (especially underneath the ball of the big toe) and common occurrence of decubitus ulcers in the sacral region.
While some ulcers are dry, a discharge is a common feature and may be thin and serosanguineous or thick and purulent if the ulcer is infected. If a discharge is present, a swab should be taken for culture and sensitivity testing. The regional lymph nodes are often enlarged due to infection, although the lymphadenopathy may be due to metastatic spread in the case of squamous cell carcinomas. If the nature of an ulcer remains in doubt after clinical examination, a biopsy with histological examination is essential. The biopsy taken is a wedge that includes a portion of the floor, the edge of the ulcer and adjacent normal skin.