This is a more technical blog post than I like to write but I think it’s important to make an effort. If you have ever required a biopsy of a suspicious looking skin lesion, then you might wonder why so many procedures over so many visits by more than one doctor was supposedly necessary. I hope by the end of this explanation, you’ll understand why a “shave biopsy” is an outdated technique for diagnosing skin cancer because not only is it incomplete, but it can actually hinder an accurate diagnosis of skin cancer and therefore lead to inadequate treatment culminating in recurrence of skin cancer, possibly spread of the cancer and avoidable death.
The common pathway for someone to have a strange looking mole evaluated is to go to their dermatologist. Somewhere in the dogma of dermatological treatment of a mole, dermatologists are taught to always do a shave biopsy rather than a more complete removal of the skin cancer. A shave biopsy is exactly what it sounds like. The mole is shaved/scraped off the skin with a razor or blade as shown in the picture to the right. The specimen is then sent to the lab for evaluation. Here’s the problem though.
Many of the most serious cancers, specifically melanoma, are staged (ie ranked as to their seriousness) by how deep the cancer extends down into the skin.
As seen in this picture to the left, the deeper the melanoma skin cancer extends, the more serious it is and the more likely it is to spread to lymph nodes and other parts of the body. That is why if a melanoma goes deep enough, doctors are trained to take a nearby lymph node to see if the melanoma has spread. But if you’ve done a shave biopsy, you may go right through the cancer and confuse the pathologist as to how deep the cancer goes. For example, if the shave biopsy undercuts the mole by only 0.2 mm then you might think the cancer doesn’t go very deep. But if there’s another 0.9 mm of cancer deeper than what the shave biopsy showed, then that means the total depth of the cancer was 1.1mm (0.9 + 0.2mm). When it comes to melanoma, millimeters make a huge difference. If a cancer is deeper than 1 mm then you should check for spread to a nearby lymph node. If it shows spread to a nearby lymph node, then you would get further treatment by way of chemotherapy to try and cure your skin cancer. But if you think it’s only 0.2 mm, then you wouldn’t get further treatment and the cancer could spread without your knowledge or further treatment.
For this reason, a shave biopsy should never be done. While they may provide a diagnosis, they may under-diagnose the depth of the cancer! This is why a true biopsy where you make an incision around the mole and cut down into the fat under the skin so you can be sure to get the entire depth of the mole/cancer will lead to a more accurate diagnosis.
When your dermatologist does a shave biopsy, it may lead to another doctor having to do a completion biopsy to get rid of all of the cancer. If you went to a plastic surgeon or a Mohs-trained dermatologist, then you have a better chance of removing the cancer all in one procedure by getting a “full thickness skin biopsy,” and avoid having to be referred to yet another doctor for a repeat biopsy and cure.
While this may seem self-serving as a plastic surgeon myself, I would be the first one to tell you to go to a Mohs-trained dermatologist to get the cancer removed in one visit. A Mohs surgeon has the unique ability to remove the skin cancer, look at it under a microscope during the same visit, confirm that all or not all of the cancer has been removed and then remove more during the same visit if necessary. Basically, you have a greater chance of being cured during one visit by one doctor (Mohs-trained dermatologist) than you do if you go to a regular non-Mohs dermatologist or a plastic surgeon. But to be clear, the non-Mohs dermatologist and the plastic surgeon can be inadequate for two disparate reasons. The non-Mohs dermatologist may provide inadequate treatment because they perform the less accurate and more pathology-distracting shave biopsy and the plastic surgeon because they can’t evaluate the skin cancer under a microscope even though they more completely remove the cancer.
So if you want a one-stop shop to get a cure and avoid what I call “the dreaded shave biopsy,” then seek out a Mohs surgeon.
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