You Need A Biopsy. Now What Happens? Part 2

By Julie Bain • Published On: August 16, 2018 • Last Updated: June 7, 2021

A tiny section of skin, sliced, stained, placed on a glass slide and magnified on a special microscope, may look pretty, but it could reveal skin cancer. Photo by Yasu + Junko; microscope provided by Accu-scope.

Skin lesions don’t come with labels, bells or whistles. Diagnosing skin cancer is way more complicated than you might think. Our two-part article gives you a peek behind the scenes of this little-understood but fascinating area of dermatology.

Part 1 described how a dermatologist performs a skin exam and determines if all or part of a suspicious spot or lesion should be removed and sent to a lab for a biopsy. It also discussed the highly trained medical specialists (dermatopathologists) who analyze the tissue, and why that is so important. Part two reveals what happens to your biopsy tissue sample, step by step, after your dermatologist ships it off to the lab.

Ever wonder what happens to that little piece of skin after it’s removed from your body? The tissue, which has been “fixed” so it doesn’t change or degrade, is transported to the lab in a small jar or bottle. It can stay at room temperature and doesn’t need to be refrigerated. Once at the lab, it is logged in, and the specimen goes through several steps of processing to help the dermatopathologist analyze it under a microscope to determine a diagnosis. See our slide show. (Lab photos courtesy of Yale Department of Dermatology).

A Biopsy Tissue Sample’s Journey

1. A technician or technologist uses lab equipment to process the biopsy tissue and prepare it for viewing under a microscope. No, this is not a kitchen drain, but a vacuum chamber that replaces water in the tissue’s cells with alcohol, a solvent and then melted wax.
2. Once the wax cools and sets, the tissue samples are encased in a hard wax block so they can be sliced into thin sections.
3. The tissue block containing the wax-embedded sample is mounted on this machine, called a microtome, for cutting.
4. Using the microtome, a technologist slices the tissue vertically, like a loaf of bread. The standard slice, or “section,” as it’s called, is about 4 or 5 microns. (A micron is a millionth of a meter, or about .00004 inches.) This will allow the dermatopathologist to see a single layer of skin cells with clarity under the microscope.
5. The technologist floats the thin strips of sliced tissue onto the surface of a water bath.
6. From the water bath, the technician lifts the tissue sections onto glass slides, which will be viewed under a microscope.
7. The technician may place one or more sections of tissue (in this case, three) on each microscope slide.
8. The slides then go into a stainer. Applying certain chemical stains helps dermatopathologists identify the type of cells on the slide when they examine it under the microscope.
9. “In the first few moments of examining a slide,” says Dr. Hitchcock (left in photo), “I might think, ‘This is a basal cell carcinoma,’ which is the most common skin cancer. But I have to rule out other possibilities, so I also think, ‘But could it be a Merkel cell carcinoma?’, which is rare and potentially deadly.” Sometimes a diagnosis is quick and clear, but in a tiny percentage of cases it can be more challenging.
10. If a diagnosis is not definite, the dermatopathologist may request unused slices from the block of tissue and use different stains called immunohistochemical stains to help pinpoint it. The doctor may also show the slides to a qualified colleague or colleagues for input, as in the previous photo.
11. Once the dermatopathologist has reached a diagnosis, whether benign, a malignant carcinoma (skin cancer) or another condition, he or she issues a detailed report. The slides are then numbered and filed for future retrieval, if necessary. After reading the dermatopathologist’s report, the dermatologist contacts the patient to discuss the results and possible treatments.