A punch biopsy is the removal of tissues for examination using an instrument called a punch. This incision is the most common technique used to obtain skin specimens to test for a number of skin disorders. A punch biopsy involves the use of basic surgical skills and is easy to learn, although it should always be performed by a specialist.
Unless a patient or doctor suspects a specific problem, a skin biopsy is generally not recommended. This is because the results rarely change ordinary treatment processes. A punch biopsy generally diagnoses problems such as melanoma, skin malignancy, benign growth, inflammatory lesion or chronic skin disorder.
If melanoma is found, further surgery is recommended, and the patient is often sent to a melanoma center for excision and removal. Other skin malignancies can be removed with a small piece of skin. Benign growths can either be left alone or excised; it is generally left up to the patient. Inflammatory lesions require further medical testing to determine the cause, and specific chronic skin disorders are identified by the biopsy so that treatment can be enacted.
During a punch biopsy, the patient can be anesthetized so that no pain is felt. Materials used for this step include nonsterile gloves, gauze soaked in an iodine solution, a syringe filled with lidocaine and epinephrine, a 30-gauge needle and a formalin container. First, the area for the biopsy must be selected. For best results, the most unusual-looking site within the lesion or the edge of a growing lesion is generally used. This area should be cleaned with the iodine solution before applying the lidocaine/epinephrine mixture with the 30-gauge needle, with anesthetizes the patient.
After this step, the doctor should switch to sterile gloves. Additional materials for the rest of the procedure include the biopsy instrument, a needle holder, iris scissors, a 21-gauge, 1 ¼-inch (3.18 cm) needle and a sterile drape. Now the doctor must identify where there is the least skin tension. The skin should be stretched around the site perpendicular to the lines of least skin tension. This stretching will result in an elliptical-shaped wound that will heal more easily.
The punch biopsy instrument should be held vertically over the skin and rotated downward, penetrating the dermis and lodging into subcutaneous fat. The skin specimen should be elevated with the anesthesia needle and the scissors used to cut the specimen free from the tissue. The wound is then closed, and antibiotic ointment and a bandage are applied.