The basics of a skin biopsy in 10 steps.
A skin biopsy can play an important role in confirming a dermatological diagnosis. For example, the procedure is the only way to verify melanoma, the most serious type of skin cancer. It can also be used to confirm that a skin tumor is benign and to diagnose inflammatory skin conditions such as eczema.
The outpatient visit
Patients see dermatologists for multiple reasons, including concern regarding a particular skin lesion or worsening of a rash. Also, patients at risk for skin cancer have total-body skin examinations performed at regular intervals. Sometimes the patient has been referred by her primary care physician because of the need for specialized expertise.
The dermatologist determines that a biopsy is needed
Biopsies of the skin are most commonly performed at the time of an outpatient visit. After conducting a total-body skin examination, the dermatologist biopsies the worrisome lesions, which could include bumps, moles, warts, rashes and discolored patches of skin.
The patient receives local anesthesia
The site for the biopsy is cleansed, usually with alcohol, and then a local anesthetic such as lidocaine is injected using a very fine needle. The patient will feel the pinch of the needle and then a burning sensation as the anesthetic is injected. A feeling of pressure may also occur when the local anesthesia is injected into a relatively taut area of skin such as the fingers or toes. If the patient is apprehensive regarding the injection, a topical anesthetic can be applied for 1 to 2 hours before the procedure to reduce the associated pain.
The dermatologist determines the correct type of biopsy to perform
The type of biopsy is determined by the size and location of the lesion, its depth and the information being sought based on the most likely diagnoses.
The different types of biopsies include:
- Shave biopsy: This is done with a scalpel when the dermatologist suspects that the condition or tumor involves primarily the top layer of the skin (the epidermis). The biopsy specimen includes the epidermis and sometimes the superficial portion of the dermis (the second layer of skin).
- Saucerization: This is done if the dermatologist envisions that the disease or tumor extends into the mid-dermis.
- Punch biopsy.This technique involves a circular blade that resembles a cookie cutter. It enters the skin with a gentle twisting motion. A punch biopsy is performed when the disease or tumor is thought to involve the deeper dermis and/or when sutures are planned.
- Excision biopsy: This has the shape of an ellipse and is done when the disease or tumor is thought to involve the deeper dermis and perhaps the subcutaneous fat. In the case of a tumor, the goal is complete removal. Sutures are used to close the wound.
The patient begins postoperative care
The patient is asked to keep the biopsy site moist by applying an ointment and to not allow a scab to form. The goal is to speed healing and minimize scarring. A small rim of redness is commonly seen at the edge of a healing wound but expanding redness, fever, chills, a discharge of pus, and/or significant pain can be signs of an infection.
Time to healing is variable and depends on the size and depth of the biopsy, its location on the body (the face heals much faster than the ankle), and underlying medical diseases. Most biopsy sites heal within 2 to 3 weeks.
The tissue is sent to a dermatopathology laboratory
Yale Medicine has an on-site dermatopathology laboratory and there are eight board-certified dermatopathologists who render the pathologic diagnoses. That's the largest academic group of board-certified specialists in the Northeast. "I feel very strongly that my biopsies should be processed by laboratory technicians who have specialized training in handling delicate skin tissue,” Dr. Bolognia says. “In addition, I want the physicians who are providing the pathologic diagnoses to have subspecialized in dermatopathology."
Yale Medicine’s physicians have helped to shape the practice of dermatopathology by making new discoveries and publishing their work.
The dermatopathology lab processes the tissue
The tiny, delicate pieces of skin are carefully embedded in paraffin wax. This creates a block that can then be cut, put on glass slides, stained, inspected and photographed. All pathology labs use special stains to determine specific types of cells, but Yale Medicine's dermatopathology lab has more than 250 stains just for skin.
If Dr. Bolognia biopsies a nevus (mole) with a darker portion that is clinically worrisome, the technicians will put special ink on the dark area. This ensures that the dermatopathologist will carefully assess the area of concern to the clinician.
Demopathologists discuss puzzling cases
Yale Medicine’s dermatopathologists hold a daily consensus conference to discuss the most challenging cases. Besides working with doctors from Yale Medicine, the lab is a referral center where consultations with dermatologists, surgeons and medical oncologists throughout New England are routinely conducted. "Every day, we all meet to go over a wide variety of challenging cases, seek multiple opinions, review relevant literature, and put our heads together to come up with an accurate diagnosis," says Jennifer McNiff, MD, the medical director of the lab.
The dermatopathologist provides a report to the dermatologist
If the dermatopathologist has questions about the patient, including specific medications or medical diseases, she calls the dermatologist who performed the biopsy before issuing the report. This is not common in general pathology labs, and is not always routine in other specialized dermatopathology labs. Yale Medicine dermatopathologists are also given the opportunity to go with the dermatologist on rounds, making them more savvy about patient care than most general pathologists.
The dermatologist contacts the patient with the results of the biopsy
If the results are benign, the dermatologist usually has results ready to share with the patient within a week. If the pathologic diagnosis is a benign tumor, then the patient is usually notified by mail or electronically via MyChart, the patient portal for the Epic electronic medical records system. In addition, those patients who sign up for MyChart have access to the actual pathology report as do the other physicians at Yale Medicine.
If the results show a skin cancer or another condition that requires an explanation, lab calls the patient. When the biopsy shows melanoma, a kind of skin cancer, the dermatologist must remove the entire area of skin that is affected. Depending on the depth of the melanoma, it's possible that physicians will want to biopsy nearby lymph nodes. The oncology section at Yale Medicine has an active melanoma unit with expertise in a wide range of conditions.