Skin Biopsy

None.

Skin biopsy is a multipurpose test used to diagnose growths, such as skin cancers and keratoses, or inflammatory skin disorders, such as psoriasis, contact dermatitis, and insect bites. Biopsy can also be a treatment when it is used to remove warts, moles, skin cancers, or other growths.

A small sample of cells is taken for examination under a microscope.

Usually none. For large biopsies, medications that can promote bleeding (such as aspirin and ibuprofen) should be stopped a few days beforehand.

The skin is cleansed, and local anesthesia is administered. This may sting briefly, but the anesthetic typically takes effect very quickly. Depending on the type of disorder suspected, one of the following forms of skin biopsy is performed:

• Punch biopsy, illustrated in figure 17.1, is used to diagnose most inflammatory diseases and many tumors. It provides a tissue sample of cells from the full thickness of the skin. The sample is obtained with a punch, an instrument that resembles a small cookie cutter with a sharp circular edge that can be pushed through the skin. When the punch is removed, it yields a core of tissue that is cut from its base with scissors or a scalpel.
• Shave biopsy, illustrated in figure 17.2, is used to remove raised noncancerous growths, such as seborrheic keratoses, and for diagnosing abnormalities suspected of being nonmelanoma cancers. The technique involves shaving the skin with a scalpel or razor blade to remove the major component of the lesion. It is not the preferred method if melanoma is strongly suspected because the tissue sample obtained may be inadequate for thorough examination if the shave is too shallow.
• Fusiform, or elliptical, biopsy, illustrated in figure 17.3, removes unusual moles or growths suspected as cancerous. The sample it yields is larger than that provided by a punch biopsy. It can be excisional, meaning that the entire growth is removed, or incisional, meaning that a portion of the growth is removed. Stitches are usually required, and there may be a fine-line scar.
• Scissors biopsy, illustrated in figure 17.4, is used when a growth is attached to the skin by a short stalk. The growth is removed with a snip of the scissors.
• Curette biopsy involves scraping off a lesion with a curette, an instrument with an oval or round blade attached to a handle. This approach is less commonly used for diagnosis because it has a greater likelihood of producing an inadequate sample (ie, it breaks the specimen into pieces, sometimes precluding microscopic evaluation of structural features that are helpful in diagnosis). More often it is used to remove growths--such as warts or basal cell carcinomas--that have been biopsied and diagnosed by another means.

• If no stitches were used, as is the case with almost all shave, scissors, curette, and some punch biopsies, a dressing (and often an antibiotic ointment) will be placed over the biopsy site. You may be told to cleanse the site, reapply the ointment, and change the dressing once or several times a day until the area heals (usually in 5 to 28 days, depending on the size and location of the biopsy). In general, it is best not to let the biopsy dry out, as a scab will delay healing.
• If stitches were used, the dressing is usually left in place or periodically changed until the stitches are removed, 5 to 10 days later, depending on the size and location of the incision. You may be told to keep the area dry during that time and to report any bleeding, swelling, or unusual redness or pain. Also, your activity may be restricted (e.g., no exercising or heavy lifting) for several weeks.

• Previous treatment of inflammatory skin diseases makes diagnosis more difficult.
• Submission of a small sample (for example, to minimize scarring) is more likely to produce an inconclusive result.
• Scar tissue from a previous biopsy makes diagnosis more difficult.

The tissue sample is examined under a microscope to determine the type and arrangement of cells. If cancer is detected, microscopic examination can determine the type of malignant cells involved.

The presence of cells that play a role in inflammation, along with characteristic changes in the upper and lower levels of the skin, helps the doctor diagnose inflammatory disease. Depending on its stage, a disease may have a variety of appearances, only some of which are specific for that disease. Therefore, biopsy may be required at two or more stages to diagnose an inflammatory disorder.

• It's highly informative.
• It sometimes provides both diagnosis and treatment.

• It's invasive.
• Follow-up care of the biopsy site is often required.

• If the biopsy was for a growth and it was benign, usually no further therapy is necessary.
• If the biopsy yielded cancerous cells, treatment to completely remove the cells will be recommended (if not done with the first biopsy).
• If the biopsy was to diagnose an inflammatory condition, treatment can be initiated or altered based on the results. If the findings from a biopsy are inconclusive, another biopsy may be ordered.