INTRODUCTION TO CHAPTER
This chapter focuses on the most common procedures in dermatology that include biopsy techniques as well as surgical procedures for removal of benign and malignant tumors. Videos of these procedures on pig’s feet and in a clinical setting can be found at www.LangeClinicalDermatology.com. The reader should seek hands-on supervised training to supplement the content in this section.
A skin biopsy is done to gather more information than is available from the patient’s history and physical examination. This information can be used to establish or confirm a diagnosis. Often clinicians hesitate to perform a biopsy. There may be concerns about the cosmetic impact on the patient, the trauma associated with the procedure, or the technical aspects involved. Some disease processes are prone to sampling error and may require multiple skin biopsies for diagnosis. This is classically the case with cutaneous T-cell lymphoma or diseases with lesions of various stages or morphology.
It is important to select the appropriate site, lesion, and technique for a biopsy. This often means focusing on the location of the suspected pathologic process, for example, the epidermis, the dermal epidermal junction, deeper dermal structures, or subcutaneous dermal fat or muscle. The likely location of the pathology will determine if a shave, punch, or an excisional biopsy is most appropriate (Table 7-1).1,2 A biopsy should not be done on lesions that are excoriated or eroded.
|Disorder||Procedures for Biopsy||Lesion or Site Selection|
Dermatoses (rash) in epidermis or superficial dermis (lesions are not indurated, sclerotic, or deep)
Dermatoses in deep dermis or fat (lesions are indurated, sclerotic, or deep)
Punch or shave
Punch, incision, or excision
|Select lesions that are characteristic or typical of the rash. Avoid old resolving lesions and excoriated lesions. If possible, avoid cosmetically sensitive areas, such as the central face|
|Vesiculobullous diseases for routine histology||Punch or shave||Biopsy new lesions 2-7 days old with bullae intact. Include the edge of blister and perilesional normal skin|
|Vesiculobullous diseases for immunofluorescence studies||Punch or shave||For suspected pemphigoid and pemphigus biopsy perilesional skin. For suspected dermatitis herpetiformis biopsy normal adjacent skin|
|Ulcers||Punch or incision||Biopsy edge of ulcer, not the necrotic center|
|Tumors that are not suspected to be of melanocytic origin||Deep shave, punch, incision, or excision||Biopsy the thickest or elevated area|
|Tumors that are suspected to be of melanocytic origin (eg, lentigo, nevus, atypical nevus, or melanoma)||Deep shave, saucerization biopsy, excision, or punch biopsy (for small lesions)3,4||Remove entire lesion for biopsy|
Shave biopsy: This is the most commonly used biopsy technique. It has the advantage of being less time consuming, yielding a good cosmetic result, and having a limited downtime for the patient. It is typically limited to processes occurring to the depth of the mid dermis. A saucerization biopsy is similar to a shave biopsy, but usually extends to the mid to lower dermis.3,5 If done too deeply, in certain locations the biopsy site may heal slowly (eg, on the lower leg) or leave a scar (eg, on the nose).
Punch biopsy: This has the advantage of providing a sample of full thickness skin, rapid healing, and uniform control. It is limited by the diameter of the punch tool, and may not be adequate for processes in the subcutaneous tissue.
Excision and incision/wedge biopsy: These are more advanced procedures that are done using a sterile technique. Advantages include an adequate sample down to the subcutaneous tissues. Margins can also be controlled and adjusted as needed. Limitations include the increased duration of the procedure and a longer healing time with a greater potential for scarring.
The next section contains a list of standard equipment that is essential for most dermatologic procedures. For each type of procedure additions to the standard tray are listed within the associated section. When surgical trays are being prepared, it is important to decide if the procedure will be clean or sterile. Shave biopsy and punch biopsy are performed with a clean technique. Deeper procedures such as excisions require a full sterile technique including a sterile tray, gloves, and disposables (eg, gauze sponges).
Seventy percent isopropyl alcohol pads/swabs, surgical marking pen, cotton-tipped applicators, and 4″ × 4″ gauze sponges.
Sterile pack containing no. 3 scalpel handle, iris scissors, and Adson or Bishop forceps with small teeth.
Dressing including bandage and sterile petroleum jelly.
Pathology materials including a biopsy bottle (with 10% formalin for routine biopsies) labeled with the patient’s name, identification number, birthdate, and the biopsy site. A pathology requisition slip and a biohazard bag are also needed.
Electrodessication and electrocautery are the most commonly used elctrosurgery procedures in dermatology. Electrodessication is primarily used to destroy tissue in superficial benign or malignant tumors and to control bleeding. It is performed using a device with a single electrode tip (monoterminal) and high voltage and low amperage (Figure 7-1).6 The electrical spark generated by this device causes desiccation (dehydration) of the treated tissue. Electrodesiccation should not be used in any patient with a pacemaker or implantable cardiac defibrillator as it can interfere with their function.
Electrocautery is performed using a device with 2 electrodes (biterminal) and low voltage and high amperage (Figure 7-1).6 The heat generated by this device destroys deeper tumors and controls bleeding by coagulation. Battery-operated disposable electrocautery devices are available. Electrocautery can be used in patients with implantable cardiac devices.
Care must be taken to properly inform the patient of the risks of any dermatologic procedure. Setting clear expectations is critical. The patient may have unrealistic expectations for scarring (or the expected lack thereof), or the anticipated duration of healing. This leads to frustration on the part of the patient and may lead to a negative impression of an otherwise normal outcome. Discussing these aspects clearly with the patient prior to the biopsy is critical, as is a review of postprocedure care. Patients do not need to stop aspirin or prescription anticoagulants for the skin procedures covered in this chapter.
After the risks, benefits, and alternatives of the procedure have been discussed, informed consent should be obtained and documented in the chart. Once the equipment is prepared, attention should turn to preparing the patient. Patient care should focus on limiting the physical and emotional trauma that may be associated with the procedure. The patient should be in a reclined, comfortable position that he or she can maintain during the entire procedure.
Injectable local anesthetics are commonly used for skin biopsies. One percent lidocaine with epinephrine added at 1:100,000 is generally standard for most dermatologic procedures. Epinephrine decreases bleeding and increases the duration dermatologic procedures. Onset of anesthesia after injection is very rapid with lidocaine. Epinephrine decreases bleeding and increases the duration of the anesthetic effect. Vasoconstriction from epinephrine may take 5 to 15 minutes for full onset. In sites with a high vascular network, like the scalp, waiting for several minutes postinjection will allow for vasoconstriction onset and greatly reduce bleeding during the procedure.
The maximum dose of lidocaine varies with the weight of the patient. The package insert recommendations for adult patients are 4.5 mg/kg (not to exceed 300 mg) for plain lidocaine and 7 mg/kg (not to exceed 500 mg) for lidocaine with epinephrine. Some patients metabolize lidocaine at a much higher rate and will require a larger dose. Other amide anesthetics vary in timing of onset and duration. A syringe is selected to match the anticipated volume of lidocaine, typically 1 to 3 cm3. Needle sizes of 26 or 30 gauge are preferred for patient comfort, but require increased pressure on the plunger and a slower rate of injection. Multiple syringes may be more appropriate for a large site as the needle will dull with repeated injections.
Lidocaine toxicity may initially present with tinnitus, lightheadedness, circumoral numbness, diplopia, or a metallic taste in the mouth. Nystagmus, slurred speech, localized muscle twitching, or fine tremors may occur with more profound toxicity. Epinephrine can lead to tachycardia and a feeling of uneasiness.
There are several things that can be done to minimize the pain and stinging associated with anesthetic injection:5
8.4% sodium bicarbonate can be added to the anesthetic at 10:1 ratio to lower the pH5
The use of a 30-gauge needle
Slowing the rate of injection to reduce injection pressure
Icing or rubbing the skin
Distraction (having the patient grasp or squeeze an object)
Topical anesthetics have a limited role in skin biopsy procedures due to the limited depth of penetration and the duration of application required to get an adequate effect. Generally they do not penetrate past the dermal epidermal junction. For younger or more apprehensive patients, a topical anesthetic can be applied to the site prior to injectable anesthesia for procedures extending into the dermis. Options include EMLA (lidocaine 2.5% and prilocaine 2.5%) cream or topical lidocaine. Absorption is slow and takes upward of 20 to 30 minutes for onset and 1 hour for maximum effect. The topical anesthesia must be applied to a sufficient thickness with the recommended number of grams as per the package insert and covered with an occlusive dressing. Peak anesthesia is achieved only after 1 hour or longer. If the need for anesthesia is anticipated, the anesthetic could be applied at home 1 hour before the procedure.
SHAVE BIOPSY PROCEDURES
A shave technique is appropriate for removal of benign superficial lesions and the biopsy of lesions that extend into the mid to lower dermis. Lesions appropriate for a shave biopsy include the following:
Seborrheic keratoses and skin tags
Nevi (when melanoma is not a concern)
Suspected squamous and basal cell carcinomas
A controlled deep dermal shave biopsy (saucerization biopsy) can be appropriate for a lesion considered for melanoma if adequate depth is obtained. However, consider a punch biopsy for smaller lesions or an excisional biopsy for larger lesions.4
In addition to the standard tray, the following items are added:
Occupational Safety and Health Administration (OSHA)–approved safety blade (eg, DermaBlade or a no. 15 blade on a scalpel handle)
Twenty percent aluminum chloride solution (eg, Drysol) for hemostasis with cotton-tipped applicators