What is punch biopsy?
Punch biopsy is one of the most widely used dermatologic procedures in primary care medicine. This technique obtains a full-thickness skin specimen for histologic assessment. A properly performed punch biopsy frequently yields useful diagnostic information. The technique is simple, rapid, and generally results in an acceptable final cosmetic appearance at the site.
What are the indications of punch biopsy?
Evaluation of skin tumors, diagnosis of skin disorders, removal of small skin lesions such as intradermal nevi and diagnosis of atypical appearing lesions.
How is punch biopsy performed?
Punch biopsy 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 the subcutaneous fat. A cylindrical core of tissue is then cut free and placed in formalin for transfer to the laboratory. Most 3- or 4-mm punch biopsy sites are closed with a single suture. The 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.
Why is punch biopsy performed?
Punch biopsy is generally performed to evaluate lesions of uncertain origin or to confirm or exclude the 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. The yield may be improved if the most suspicious or abnormal-appearing area (darkest, most raised, or most irregular contour) is biopsied. If the suspicion for melanoma is high, it is preferable to perform excisional biopsy to have the entire lesion available for evaluation.
What are the disadvantages of performing punch biopsy for suspected cancer lesions?
Punch biopsy used for basal and squamous cell carcinoma has one disadvantage. After these cancers have been biopsied using punch technique, the physician is obligated to perform a definitive excisional technique. Superficial techniques that are frequently employed for these lesions, such as curettage and electrodesiccation, may miss cells that have been driven deeper by the punch instrument. Physicians should not fear performing punch biopsy on a melanoma, because the biopsy does not alter the natural course of the disease, and a prompt biopsy expedites definitive treatment.
What should physicians be oriented of when performing a punch biopsy?
Physicians should be aware of the 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 such as arteries, tendons, or nerves. Punch biopsy on the upper cheek can damage the facial or trigeminal nerves, and punch biopsy of the lateral digits or of the thin eyelids should be approached with great caution.
What are the implications of these factors on performing a punch biopsy?
Lesions overlying anatomic structures likely to be damaged by full-thickness skin biopsy: on the eyelid (globe), on the dorsum of the hand in elderly patients (tendons), or on the upper cheek (facial nerve) or fingers (digital nerves and arteries) should be contrindicated. Also foot and toe lesions in elderly patients or those with peripheral vascular disease.