Topic

• Introduction
• Indications
• Contraindications
• Procedure
• Coding Information

Figure(s)

• Selecting the Biopsy Site
• Preparing for the Closure of the Biopsy Site
• Technique to Use the Punch Biopsy Instrument
• Obtaining the Specimen

• Punch biopsy obtains a full-thickness skin specimen for histologic assessment. It is performed with a circular blade known as a trephine, which is attached to a pencil-like handle.
• The instrument is rotated using downward pressure until the blade penetrates into subcutaneous fat. A cylindrical core of tissue is then cut free and placed in formalin for transfer to the lab.
• Most 3- or 4-mm punch biopsy sites are closed with a single suture. 2-mm punch biopsy sites frequently do not require suture closure, and Monsel's solution can be used for hemostasis if the wound is allowed to granulate.
• Punch biopsy is generally performed to evaluate lesions of uncertain origin or to confirm or exclude presence of malignancy. This biopsy technique is considered the method of choice for many flat lesions. Suspected melanomas can be evaluated by this technique, especially when the lesion is too large for easy removal. Yield may be improved if most suspicious or abnormal-appearing area is biopsied.
• If suspicion for melanoma is high, it is preferable to perform an excisional biopsy to have the entire lesion available for evaluation. Physicians should not fear performing punch biopsy on a melanoma, because biopsy does not alter the natural course of disease, and prompt biopsy expedites definitive treatment.
• After basal and squamous cell carcinomas have been biopsied using the punch technique, the physician is obligated to perform a definitive excisional technique.
• Physicians should be aware of underlying anatomy when performing a punch biopsy. Certain areas of the body where there is little subcutaneous tissue pose the greatest threat of damaging underlying structures—e.g., arteries, tendons, or nerves. Punch biopsy on the upper cheek can damage facial or trigeminal nerves, and punch biopsy of lateral digits or of thin eyelids should be approached with great caution.

• Evaluation of skin tumors: e.g., basal cell carcinoma or Kaposi's sarcoma
• Diagnosis of bullous skin disorders: e.g., pemphigus vulgaris
• Diagnosis of inflammatory skin disorders: e.g., discoid lupus
• Removal of small skin lesions: e.g., intradermal nevi
• Diagnosis of atypical appearing lesions: e.g., atypical mycobacterial infection

• Lesions overlying anatomic structures likely to be damaged by full-thickness skin biopsy: on eyelid (globe), on dorsum of hand in elderly patients (tendons), or on upper cheek (facial nerve) or fingers (digital nerves and arteries) (relative)
• Subcutaneous lesions that cannot be reached with punch instrument (erythema nodosum)
• Foot and toe lesions in elderly patients or those with peripheral vascular disease

• The punch biopsy instrument (i.e., trephine) has a plastic, pencil-like handle and circular scalpel blade. The blade attaches to the handle at the hub of the instrument.
• Select a punch biopsy instrument of sufficient size (i.e., 4 or 5 mm) to obtain adequate tissue for histologic assessment while minimizing size of scar (i.e., 3-mm instrument for biopsy on face).
• Select the best site for biopsy. Perform punch biopsy at the most abnormal-appearing site within the most abnormal-appearing lesion or at the edge of an actively growing lesion.
• Biopsy skin tumors in the center of lesion (Fig. 10-1A), and biopsy bullous lesions at the edge (Fig. 10-1B.)
• Pitfall: Do not biopsy lesions that have been traumatized, scratched, or significantly modified. Biopsy of a traumatized lesion rarely provides useful information. Provide the pathologist with information on the age and sex of the patient, current medications, appearance of lesion, and body location to increase the chance of gaining useful clinical information from the biopsy. Remember that biopsy of nonspecific rashes, particularly in younger individuals, rarely provides additional information that benefits clinician.
• Prepare for closure of punch biopsy site when performing technique. A circular defect is not easily closed, but an oval or elliptical defect approximates well.
• After administration of local anesthesia, stretch the skin 90 degrees (i.e., perpendicular) to lines of least skin tension using the nondominant hand (Fig. 10-2B). The lines of least skin tension for the arm are circumferential (i.e., perpendicular to long axis of arm) (Fig. 10-2A.)
• After performing punch biopsy, relax the nondominant hand, and the circular defect becomes more oval. Close the defect with a single, small-caliber suture—e.g., 5-0 nylon (Fig. 10-2C.)
• Rotate the punch biopsy instrument with downward force when performing the biopsy (Fig. 10-3). Turn the blade around its handle with back-and-forth motion until instrument traverses full thickness of skin. Be prepared to stop downward pressure as soon as the instrument penetrates through the skin.
• When trephine penetrates skin into subcutaneous fat, the operator often notices a "give.''
• Pitfall: Historically, physicians were instructed to insert the instrument up to the hub. With larger punch instruments, the blade must penetrate 3/8 in. of skin to reach the hub. Going to the hub is appropriate where skin is thick (e.g., upper back) but can damage underlying structures—e.g., nerves or tendons—where the skin and subcutaneous tissue is thin. Do not push the instrument to the hub when performing a punch biopsy on the upper cheek or dorsum of the hand.
• Cut specimen free from subcutaneous fat after cylindrical cut is made through skin (Fig. 10-4). Lift specimen with needle used to anesthetize skin site, and then cut it free at the base (beneath dermis) using sharp iris scissors.
• Pitfall: Many pathologists refuse to examine a skin biopsy specimen that has been crushed. Punch biopsy specimens often are crushed when they are elevated using Adson forceps. Elevate specimen with anesthesia needle to avoid crush artifact.

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