9.3.3 Basics of Dermatosurgery Techniques

Dermato-surgery refers to surgical procedures involving mainly the skin, its appendages and the underlying subcutaneous fat and fascia. These may be performed in outpatient or inpatient settings and are mostly performed using local anaesthesia.

Dermato-surgery is indicated for obtaining a skin biopsy for histopathological analysis, for removal of malignant tumours of the skin or for removal of benign skin lesions because of local symptoms including hidradenitis or sweat gland removal or for cosmetic purposes, for therapy of varicosis (stripping), for wound care (transplantation) and for hair transplantation.

Different techniques are used in the surgical management of benign and malignant skin lesions. The most frequently used techniques include incisional biopsy, punch biopsy, shave biopsy, primary excision, with primary closure, shave excision, curettage, electrosurgery (e.g. diathermy, coagulation, cautery). In addition, more advanced techniques comprise Mohs' micrographic surgery, complex reconstruction using flap procedures and skin grafting. A combination of different techniques is often necessary.

The choice of technique depends primarily on purpose (e.g. diagnostic or therapeutic), the diagnosis (benign or malignant), local spread and growth (superficial or infiltrating) and the size and anatomical site of the lesion. Patient profile (age, co-morbidity, drugs) and preference combined with the expertise of the surgeon are also very important factors.

Fig. 1

The object is to obtain a diagnostic full-thickness skin specimen for histopathology. It may involve the use of a scalpel (elliptic excisional biopsy, see below) or a cylindrical blade attached to a handle (i.e. punch biopsy). It is best to choose a lesion of recent onset, or the most abnormal-looking edge of an enlarging lesion for a diagnostic biopsy.  

Skin lesions suitable for punch biopsy include all kinds of skin tumors and precancerous lesions. It should however not be used for larger melanocytic lesions or those which are showing clinical atypia, which should be excised. The chosen site should be marked and infiltrated with a local anesthetic. Stretch the skin perpendicular to the skin tension lines so that the punch defect will have an elliptical shape. The punch is held vertically over the skin and rotated down until the subcutaneous tissue (visible fat tissue). The specimen is then removed and gently handled to prevent crush artefacts. A separate punch biopsy may be taken from perilesional skin for direct immunofluorescence (e.g. to diagnose autoimmune blistering diseases). Wound closure is usually accomplished by using a single interrupted suture and hemostasis is ensured by pressure and bandage. Skin specimens should always be sent to histopathology.

The technique is similar to shave excision (see below) with the difference that the main purpose is to obtain a specimen for histopathology.  

Fig. 2

Lesions growing mainly above the skin surface can be shaved off as a tangential excision using a scalpel blade or razor blade. Curettage refers to the use of a sharp spoon-shaped instrument to scrape off a superficial skin lesion. Light cautery or other methods of hemostasis (e.g. iron nitrate solution) is used and the wound is left to heal by secondary intention. Examples of skin lesions that may be removed this way include skin tags, filiform viral warts and seborrheic keratosis. The technique may result in unsightly scars and lesions may recur. In some cases curettage may be followed by cryotherapy or photodynamic therapy.

Fig. 3

Firstly, it is important to identify the margins of the lesion in good light and to mark out with a surgical pen a fusiform or elliptical shape around the lesion. Its form should be 2-3 times as long as it is wide and follow the skin tension lines (Langer lines). Thereafter inject a local anesthetic, (usually 1% lidocaine with adrenaline) using a fine needle into the superficial dermis. Wash the surgical area with an antiseptic solution (e.g. alcohol) and apply surgical guards for an aseptic technique. It is important to stabilize the incision area by traction with the fingers. By applying controlled pressure on the scalpel, carry out the cut along marked lines vertically with the angle of the blade. It is usually necessary to cut until the subcutaneous tissue, and remove the specimen. The specimen should be placed entirely in a labeled vessel and numbered. It may be necessary to use the scalpel or scissors to undermine the skin edge below the dermis. This will loosen the overlying skin and decrease tension.

Complex reconstructions using different flap techniques are used in situations where primary closure is not possible, e.g. due to large excisions or anatomical sites where tension may cause functional impairment. Local, regional or distant flaps can be used and there are many different techniques available (advancement flap, rotation flap, transposition flap ). The basic principle is to reconstruct a skin defect with a lifted skin flap from a donor site and move it to a recipient site with an intact blood supply.

Comparable to complex reconstructions using flaps, skin grafts are used to cover large or complex excisional defects. Skin grafting involves the transplantation of skin, usually from the same patient but from another anatomical site. Typical donor sites are the preauricular region or the lateral thigh. The transplanted tissue does not have an intact blood supply and therefore relies on growth of new blood vessels. Principally, there are two types of skin grafts: split thickness skin graft (removal of a thin layer of skin from donor site to close a defect) and full-thickness skin graft (punching or cutting whole skin away from the donor site to close small defects or to treat vitiligo or to transplant hair). 

Mohs' micrographic surgery is a surgical technique in which the complete excision of skin cancer is controlled by microscopically controlled margins. The technique is used in situations where high cure rates with maximizing preservation of healthy tissue is needed, e.g. high risk basal cell carcinomas on the face. Here, the skin cancer is gradually removed in stepwise phases. After each phase of excision, the margins are immediately microscopically examined for remaining cancer cells and this process is repeated until full removal of all cancer cells. Several other techniques are used for the removal of tissue (fresh versus fixed tissue technique).

Electrosurgery is used for hemostasis and desiccation of tissue using high frequency (0.1-1 MHz currents). Methods include electrodesiccation (cautery, contact of electrode with skin, deeper tissue injury), electrocoagulation (diathermy, bipolar forceps, mostly hemostasis) and electrosection (undamped wave, cutting without haemostasis or adjacent tissue injury). Benign lesions can easily be scraped off when light electrodessication is used first. Electrosurgery destroys tissue and prevents accurate histopathological examination. Cave: Ask about the presence of a cardiac pacemaker.

Local anesthesia involves the use of topical anesthetics and injections of local anesthetics directly into the tissue (infiltration) or into the vicinity of peripheral nerves (nerve blocks). Topical anesthesia may be useful for small procedures, e.g. scissor snipping of skin tags. The anesthetic cream is applied 1-2 h before the procedure (e.g. eutectic mixture of prilocaine and lidocaine, cream or plaster). Most skin procedures require an subdermal anesthetic, such as lidocaine (xylocaine). After injection the onset of action is rapid in a few minutes and lasts one to three hours. The addition of adrenaline 1:100,000 extends duration and may control bleeding (but avoid adrenalin in acral lesions).

Methods of hemostasis for superficial bleedings include local pressure and hemostatic solutions (e.g. iron or aluminum chloride) applied with cotton tips. In deeper bleeding, typically after excisions with primary closure or more complex reconstructions using flap procedures, pinpoint diathermy is used.

For wound closure there are several techniques. The most used is a single layer closure using simple interrupted sutures tied using the needle holder. The stitches should be arranged equally on each side including at the least the whole dermis. The surgical knot is tightened so that the edges of the wound are lightly in contact to avoid scarring. In some sites a continuous suture may provide more satisfactory cosmetic results. Deeper and larger wounds may require subcutaneous sutures to eliminate dead space (e.g. hematoma and infection risk).

After suturing, light pressure should be applied to ensure that the bleeding has completely stopped. Thereafter the wound should be cleaned and dressings should be applied. In most cases the first dressing should be removed after 1-2 days. Sutures should be removed after the procedure depending on body site, the size of the wound and the amount of tension on it (e.g. face 5-7 days, arms and trunk 7-10 days, lower legs 10-14 days).

Typical complications after skin surgery are wound infections, hematoma formation, wound dehiscence and scarring. Scar formation can cause cosmetic problems but also have functional impairments (contractures of joints, ectropion of the eye lid). In rare cases peripheral nerve damage may lead to paresthesia and impairment of motoric innervation (eye lid ptosis). 

Procedures should be performed in aseptic circumstances to avoid wound infections. Based on patient risk factors, prophylactic systemic antibiotics are sometimes administered. Hematoma formation can be prevented by meticulous hemostasis and risk management of possible anticoagulant drugs. Wound dehiscence and scarring is best prevented by minimizing tension of the excisional defect and adequate suturing techniques.

To reduce scarring after dermato-surgery excisions should be performed in right angles to the muscle pull directions or parallel to skin tension lines (Langer lines). Scars are at first red and firm, but usually after some months the induration and erythema reduce leaving a softer scar that is paler than the nearby skin. Scars may stretch if there is wound tension. There is an increased risk of scarring if the patient has had prior hypertrophic scars or keloids (consider ethnic susceptibility), if the direction of the scar is not parallel to natural lines and in some high-risk anatomical sites (upper sternum, shoulders, joints). Visible scarring may also be evident if complications like hematoma formation, wound infection or wound dehiscence occur after the procedure.