For skin biopsies (and most skin surgery procedures), local anesthesia with 1% lidocaine with epinephrine (1:1000,000 or 1:2000,000 dilution) is recommended.
The epinephrine decreases bleeding and keeps the anesthetic in the area it was injected.
Draw up 1 to 2 mL for shave or punch biopsies and 3 mL for larger biopsies.
Methods to decrease pain caused by injections include the following:
This is used for the diagnosis and therapeutic removal of superficial (epidermal and upper dermal) skin lesions, such as melanocytic nevi, warts, seborrheic and solar keratoses, pyogenic granulomas, and skin tags, as well as other benign and certain malignant skin tumors.
It is used to obtain biopsy specimens to confirm skin disease before a more definitive surgical procedure that may be required (e.g., basal or squamous cell carcinoma).
It is very useful for flattening and diagnosing nevi, particularly in the facial area.
Advantages
Disadvantages
It is not indicated for lesions or diseases that extend into the subcutaneous layer.
It is not indicated when a full-thickness biopsy is necessary (e.g., deep inflammatory dermatoses).
It should not be performed on lesions suspected of being melanoma because of the difficulty in clinically determining the maximum thickness or extent of a lesion.
Technique
Anesthetize the area adjacent to the lesion with an injection of 1% plain lidocaine with or without epinephrine into the superficial dermis using a 30-gauge needle. Use lidocaine without epinephrine in finger and toe areas to avoid vascular compromise (Fig. 35.13A,B).
Inject so that the lidocaine creates a wheal and elevates the lesion above the surrounding skin.
Applying traction with the thumb and index finger of the free hand on either side of the lesion stabilizes it.
Place a no. 15 scalpel blade flat on the skin; use in a slight sawing motion with smooth strokes parallel to the skin surface and draw the middle of the blade through the lesion.
Release traction when the lesion becomes sufficiently free; use small forceps with teeth to hold and elevate the lesion to complete the “shave” and then to deliver it to a bottle of formalin.
Use low-intensity electrocautery or further shaving to “feather” jagged edges.
Apply Monsel solution (ferric subsulfate) or aluminum chloride 35% with a cotton pledget (Q-Tip) to rapidly achieve hemostasis. Hemostasis is possible only if the field is wiped dry of blood.
Send all pigmented lesions to a pathologist; obvious nonpigmented skin tags do not need to be sent for pathologic evaluation.
Scissor (Snip) Biopsy and Snip Excision 
Certain elevated or pedunculated lesions, such as warts, nevi, seborrheic keratoses, and skin tags, are ideally suited for removal with a shave or snip (with a scalpel or scissors).
Many can be precisely removed level to the skin very quickly.
Technique
It may be possible to snip off thin, small lesions without any anesthesia; larger lesions require the administration of local anesthesia. Anesthetize the area of larger lesions in the same manner as for scalpel shave excisions (see above) (Fig. 35.14).
Gently hold the lesion with small forceps and pull it to cause slight tenting of the epidermis and upper dermis.
Use straight or curved sharp iris scissors with fine points to snip off the lesion.
Use light electrodesiccation at the base of the lesion, or apply a styptic (e.g., Monsel solution) or aluminum chloride 35% to cause hemostasis (stinging or burning may result if lesion has not been anesthetized). Local pressure is also effective in preventing blood flow.
Trim away any slight elevation or irregularity of the margin with scissors.
A punch biopsy involves the use of a 3- to 5-mm cylindric cutting instrument (“punch”) to remove all or part of a lesion.
This method is most useful for biopsy of relatively flat, inflammatory lesions such as seen in psoriasis, lichen planus, and vasculitis.
Disadvantages
The sample may not adequately show the entire lesion; a second technique (i.e., an elliptical biopsy) may be necessary for adequate demonstration of complete tumor architecture.
It is not suited for lesions primarily located in the subcutaneous tissue.
Areas to be avoided are the digits, around the facial nerve, or in any region where the operator is unfamiliar with the underlying anatomy.
Technique
In contrast to shave biopsy, a more thorough approach to sterile technique is necessary (Fig. 35.15).
Cleanse the lesion and surrounding skin with 70% isopropyl alcohol, povidone-iodine (Betadine), or chlorhexidine (Hibiclens).
Anesthetize the area with an injection into the deep dermis with 1% lidocaine with or without epinephrine, using a 30-gauge needle.
With the fingers of the nondominant hand, stretch the skin at a 90-degree angle to the natural wrinkle lines.
Gently push the punch downward into the dermis while advancing it slowly and twirling it back and forth until it “gives.” Caution should be used over thin tissue or over vital structures.
It is important to push the punch deep enough to obtain underlying fat tissue for an adequate sample.
Withdraw the punch along with the tissue sample. If the sample does not come out with the punch, cut it at the base while depressing the surrounding skin.
Remove the tissue specimen using forceps with teeth and then, if necessary, cut the specimen with iris scissors. Take care to avoid crushing the specimen and distorting the tissue sample.
Place firm pressure on the circular skin wound to curtail bleeding.
A one or two sutures for closure is all that is usually necessary.
Outline