Physical Forms of Treatment

27
Physical Forms of Treatment

The skin can be treated in many ways, including surgery, freezing, burning, ultraviolet radiation and lasers. Some broad principles are discussed here.

Surgery

As our population ages, and becomes more concerned about appearances, requests for skin surgery are becoming more common. The distinction between traditional dermatological surgery and cosmetic surgery is blurring. There are few over the age of 50 years who do not have a benign tumour (see Chapter 20) that they consider unsightly and wish to have removed. There are also many who are unhappy with a skin damaged by cumulative sun exposure (p. 265), or concerned about medically trivial abnormalities on their face. To term the treatment of all these as ‘cosmetic’ seems harsh. Health care systems cannot cover the cost of treating all such problems, but family doctors and dermatologists should be able to discuss with their patients any recent developments in phototherapy, laser treatment and specialized surgery that might help them. For example, doctors should be able to explain that diode lasers can remove unwanted hair permamently without visible scarring, and the pros and cons of such treatment, as well as supplying the names of specialists.

Preparation

No surgery is minor. Always mark the site prior to the procedure to reduce error. Use an aseptic technique, if possible in a designated room with appropriate facilities. There are few exceptions but these include bedside biopsies on unconscious patients and those too ill to move. Most biopsies can be performed with clean gloves and isopropyl alcohol prep to the skin (Figure 27.1). Excisions and Mohs’ reconstruction should be performed with additional antiseptic prep (chlorhexidine or povidone-iodine solution) and sterile gloves (Figure 27.2). Pre-packed sterile packs of instruments and swabs have made these procedures much easier. Local anaesthesia is usually adequate for skin biopsies, excisions, Mohs’ surgery and reconstruction. Most dermatologists use 1 or 2% lidocaine. The addition of adrenaline (epinephrine) constricts local blood vessels to prolong the anaesthetic effect and reduce bleeding (Formulary 2, p. 425).

images — **Figure 27.1** An example of a biopsy tray setup with clean gloves.

Antibiotic prophylaxis

Antibiotic prophylaxis is effective in reducing bacteraemia during major surgery, but it probably does not prevent endocarditis or haematogenous total joint infection after simple skin surgery. Routine dermatological surgery (including biopsies, curettage and simple excisions) performed on clean intact skin carry a very low risk of wound infection (1–4%). Because of the low risk of bacteraemia in the setting of skin surgery, British guidelines (see Further reading) suggest that antibiotic prophylaxis for endocarditis is not recommended for routine dermatological surgery even in the presence of a pre-existing heart lesion (e.g. prosthetic valves, history of bacterial endocarditis, congenital cardiac malformation, hypertrophic cardiomyopathy, valvular dysfunction and mitral valve prolapse with regurgitation). Similarly, routine antibiotic prophylaxis is not necessary even in patients at high risk (those within the first 2 years of a joint replacement). However, in locations where the risk of wound infection increases to 5–15%, such as eroded or ulcerated skin, respiratory or buccal mucosa, groin and lower leg, antibiotic prophylaxis should be considered in patients at high risk of bacterial endocarditis or joint infection.

Protection against blood-borne infections in dermatological surgery

The risk of contracting a blood-borne virus infection from a patient by a needle stick or scalpel injury during a surgical procedure is low in the United Kingdom. It varies with the individual virus; it is higher with hepatitis B (HBV) (5–40%) than with hepatitis C (HCV) (3–10%) and HIV (0.2–0.5%). The highest risk of acquiring HIV is following percutaneous injury involving a hollow needle that has been in the vein or artery of an HIV positive patient with a high viral load. The risk of acquiring HIV through mucous membrane exposure is less than 1 in 1000 and there is no evidence of risk from blood in contact with intact skin.

These days, any patient can carry an undiagnosed infection, so gloves should be used for all surgical and other procedures where there is risk of contacting blood or body secretions. When operating on a high risk patient the surgeon should wear not only gloves, but also a water-repellent gown, protective headwear, a mask with visor and protective footwear. Other good preventative measures include:

Good basic hygiene with regular handwashing;
Cover of existing wounds; and
Safe procedure for the handling and disposal of needles and blades.

Immunization is currently only effective against HBV infection. All medical staff who come into contact with blood or blood-related products should be immunized against this virus.

Immediate action after a needle and/or scalpel injury.

Wash off splashes on the skin with soap and running water.
Encourage bleeding if the skin is already broken. Disinfect the wound using an ample amount of soap and water. If contact with mucous membranes, flush thoroughly with water or saline solution.
Record the source and nature of the injury.
Immediately consult the local medical adviser about risk assessment and prophylaxis with antiviral drug(s).
If the source of the blood is known, the nature and implication of the injury should be explained to the source patient. Efforts should be made to obtain consent from the source patient to sample blood for testing of HBV, HCV and HIV.

Further information can be found in the British Association of Dermatologists’ guidelines (see Further reading).

Skin biopsy

The indications for biopsy, and the techniques employed, are described in Chapter 3. Briefly, shave or punch techniques can be used to obtain a sample specimen for histopathological examination.

Excision

Excision under local anaesthetic, using an aseptic technique, is a common way of removing small tumours for histopathologic examinatation and surgical cure. First, the lesion must be examined carefully and important underlying structures (e.g. the temporal artery) noted. If possible, the incision should run along the line of a skin crease, especially on the face. If necessary, charts or pictures of standard skin creases should be consulted (Figure 27.3). After injection of the local anaesthetic the lesion is excised as an ellipse with a margin of normal skin, the width of which varies with the nature of the lesion and the site (Figure 27.4). Benign lesions can be removed with 1–2 mm margins. Recommended margins for basal cell (BCC) and squamous cell carcionomas (SCC) is usually 4–5 mm and for atypical naevi is 3–4 mm. The length of the fusiform shape should be about 3–4 times the width to minimize redundant cones of tissue or ‘dog-ears’ at the tips. The scalpel should be held perpendicular to the skin surface and the incision should reach the subcutaneous fat. The ellipse of skin is carefully removed with the help of a skin hook or fine-toothed forceps. Larger wounds, and those where the scar is likely to stretch (e.g. on the back), are undermined carefully to mobilize the tissue and reduce wound tension. It is then closed in a layered fashion – the subcutis and dermis is closed with absorbable sutures (e.g. Dexon) before apposing the skin edges without tension using non-absorbable interrupted or running sutures such as nylon or Prolene (see Further reading for precise techniques of suturing). Stitches are usually removed from the face in 5–7 days and from the trunk and limbs in 10–14 days. Artificial sutures (e.g. Steri-Strip) may be used to take the tension off the wound edges after the stitches have been taken out (Figure 27.5).

Shave excision

Many small lesions are removed by shaving them off at their bases with a scalpel tangential to the skin surface under local anaesthesia. This procedure is suitable only for exophytic tumours that are believed to be benign. Some cells at the base may be left and these, in the case of malignant tumours, could lead to recurrence.

Saucerization excision

This modified shave excision extends into the subcutaneous fat. Instead of tangentially shaving off the growth, it is ‘scooped’ out, leaving a crater-like wound. The technique is used to remove certain small skin cancers and worrying melanocytic naevi. It tends to leave a more noticeable depressed white scar when compared with a shave excision but the technique provides tissue that allows the dermatopathologist to determine if a tumour is invading and to measure tumour thickness if the lesion is a melanoma. Furthermore, the technique may ensure complete removal more adequately than shave excision.

Cryotherapy

Freezing damages cells by intracellular ice formation. The ensuing thaw compounds this damage by osmotic changes across cell walls and by vascular stasis. The damage is semi-selective in that cellular components are more susceptible to cold injury than stromal ones. There is also some variation in susceptibility between different cells, for example melanocytes are more vulnerable to cold injury than keratinocytes.

Cryotherapy is a most convenient procedure for use in general outpatient and domiciliary practice. Further advantages include its cost effectiveness, its speed and suitability for those who fear surgery, and its lessened chance of transmitting blood-borne infections. These have to be weighed up against its two main disadvantages: short term pain and no histological confirmation of the lesion being treated. Several freezing agents are available. Liquid nitrogen (–196°C) is the most popular and is now used more than carbon dioxide snow (‘dry ice’, –79°C). It is effective and used often for viral warts, seborrhoeic keratoses, actinic cheilitis, actinic keratoses, simple lentigos and some superficial skin tumours (e.g. intraepidermal carcinoma and lentigo maligna). It is applied either on a cotton bud or with a special spray gun (Figure 27.6). The lesion is frozen until it turns white, with a 1–2 mm halo of freezing around. Two freeze–thaw cycles kill tissue more effectively than one but are usually unnecessary for warts and some keratoses (Figure 27.7). Treatment of BCC with liquid nitrogen cryosurgery requires significantly longer freezing time to reach tissue temperatures of –50 to –60°C. Patients should be warned to expect pain and possible blistering after treatment. Care should be taken when treating warts on fingers as digital nerve damage can follow over-enthusiastic freezing. Standard freeze–thaw times have been established for superficial tumours (see Further reading) but temperature probes in and around deep tumours are needed to gauge the degree of freezing for their effective treatment. A crust, including the necrotic tumour, should slough off after about 2 weeks. As melanocytes are very sensitive to cold injury, hypopigmentation at a treated site is common and may be permanent.

Curettage

Curettage under local anaesthetic is also used to treat benign exophytic lesions (e.g. seborrhoeic keratoses; Figure 27.8) and, combined with electrodesiccation (p. 371), to treat some BCC. Its main advantage over purely destructive treatment such as laser or liquid nitrogen is that histological examination can be carried out on the curettings. As morphology of the tumour is fragmented, the curetting technique does not allow for histological confirmation of tumour clearance and should not be used if there is uncertainty about the primary diagnosis. A sharp curette is used to scrape off the lesion and haemostasis is achieved by local haematinics, by electrocautery or electrodesiccation. The wound heals by secondary intention over 2–3 weeks, with good cosmetic results in most cases.

When a BCC is treated, the curette is scraped firmly and thoroughly along the sides and bottom of the tumour (the surrounding dermis is tougher and more resistant to curettage than the carcinoma) and the bleeding wound bed is then electrodesiccated aggressively. This stops bleeding and destroys a zone of tissue under and around the excised tumour to provide a tumour-free margin. The process is repeated once or twice at the same session to ensure that all of the tumour has been removed or destroyed. Only small BCC outside the skin folds should be treated in this way. The recurrence rates are relatively high for tumours in the nasolabial folds, over the inner canthi and on the nose, glabella and lips. The technique should not ordinarily be used for infiltrative or sclerosing BCC, invasive lesions larger than 1–2 cm, rapidly growing tumours or for those with micronodular features on histology.

Electrosurgery

This is often combined with curettage, under local anaesthesia, to treat skin tumours. The main types are shown in Figure 27.9.

Microscopically controlled excision (Mohs’ micrographic surgery)

This form of surgery for malignant skin tumours is time-consuming and expensive, but allows for greater tissue conservation and the highest cure rate compared with excision or curettage. Mohs’ surgery was pioneered by Dr Frederic E. Mohs in the 1950s. In the United Kingdom, the Mohs surgeon is normally a consultant dermatologist who has undertaken additional fellowship training in Mohs’ micrographic surgery, dermatopathology of skin tumours and reconstruction. A surgeon using Mohs’ technique functions as both the surgeon and the pathologist, which allows for precise mapping and margin control. First, the tumour is removed with a narrow margin, usually 1–2 mm instead of the usual 4–6 mm required with standard excision. The excised specimen is then marked at the edges, mapped and rapidly frozen for histological processing in horizontal sections. This allows for microscopic examination of 100% of the tissue margin. In contrast, conventional histologic sections requires formalin fixation and takes several days to process. The cross-sectional slices of representative tissue or ‘bread loaf’ in conventional sections also examines less than 1% of the true margins.

In most cases, each stage of Mohs’ surgery requires less than 1 hour to process and the entire procedure is performed under local anaesthetic. If the tumour extends to any margin, further tissue is removed from the appropriate place, based on the markings and mappings, and again checked histologically. This process is repeated until clearance has been proved histologically at all margins. The resulting wound can then be closed directly, reconstructed with a flap, covered with a split skin graft or allowed to heal by secondary intention.

In general, Mohs’ surgery is useful to treat skin cancers at high risk of recurrence (Figure 27.10). There are many factors that have an effect on recurrence rate including histological features, location and patient features (Table 27.1). Low risk lesions can be treated with a number of surgical modalities mentioned in this chapter including excisional surgery and electrodessication and currettage (Table 27.2). In addition, patients who cannot undergo surgical treatments (such as the very elderly and those in poor health) may benefit from radiotherapy, topical immunotherapy with imiquimod (Formulary 1, p. 405) and non-surgical therapies.