Malignant melanoma usually arise from pigmented lesions, like freckles and moles. It is the worst form of skin cancer due to its ability to spread throughout the body. In fact, advanced lesions drop 5-year survival to below 50%! When melanomas grow, they may spread sideways or deep. It is the deeper variety that is most dangerous. Once they reach a certain depth, they have a higher likelihood to enter the lymphatic system or bloodstream, and may spread to distant sites.

If you tend to form freckles, moles, or pigmented spots you are at higher risk. If you’ve had a lot of sunburns or intense sun exposures, your risk also goes up. But can you tell if a melanoma has formed? Here is a helpful mnemonic (ABCDE):

Is the lesion (A)symmetric?

Are the (B)orders irregular, scalloped, or poorly defined?

Are there different (C)olors within the lesion?

Is the lesion (D)iameter greater than 6 mm (about an eraser head)?

Has the lesion (E)volved in size, shape, or color?

Any “yes” to the above should prompt you to see a dermatologist.

Let’s say you have a pigmented lesion that has enlarged, become irregular, or gotten darker. The only way to know it is melanoma is for a surgeon to obtain a tissue biopsy and a pathologist to look at it under the microscope. The pathologist can identify aggressive characteristics – we believe some of the most important are how deep the cancer has grown and how fast the cancer cells are multiplying. This is how we determine the cancer stage (i.e. how advanced it is). But the pathologist doesn’t have a chance unless the surgeon removes an adequate biopsy. This biopsy does not have to be wide, but it must be deep enough to capture the entire depth of the melanoma. Older methods of shaving some tissue off the top just won’t cut it.

Now, let’s say you are diagnosed with a melanoma. How do we know it hasn’t already spread? Lymphatic spread may present as swollen lymph nodes in the neck. Spread through blood vessels may lead to internal organ dysfunction. In these cases, a body scan (CT, MRI, X-ray, etc) is indicated.

However, microscopic spread may not manifest in any signs or symptoms and cannot be seen with a scan. Therefore, a body scan is usually not helpful for lesions of an early stage. For some early and intermediate disease, a “sentinel” lymph node biopsy (see below) may be helpful to check for microscopic spread. Unfortunately, for advanced disease the assumption must be that that the cancer has already spread. Early diagnosis is key!

If a melanoma has not spread, surgically removing it may provide a cure. But a melanoma may have “satellite” cells that have jumped off the primary lesion, so just removing what we see has a higher risk of it coming back. For this reason, surgeons need to remove not only the lesion but also a “margin” of normal-appearing tissue around the lesion. This margin depends upon the depth of the lesion.

Even with this margin of tissue, the only way a surgeon can know that the entire melanoma has been removed is to have a pathologist specially prepare the tissue and treat it with melanoma identifying stains. This helps to ensure that no maverick melanoma cell will be missed. This process may take a day or more, so often the surgical area cannot be repaired until the results are in. If any melanoma cells are close to a margin, more tissue may need to be removed. Repairing the area prematurely, may be counterproductive or increase the risk that the cancer will return.

We cannot say for sure whether any microscopic melanoma cells have spread. The old argument was that we should go ahead and remove all the hundreds of neck lymph nodes (just in case). Over time, the evidence has not supported this practice. Instead, a method call “sentinel” lymph node biopsy has been developed. In short, we figure out which lymph nodes are closest to the diagnosed melanoma and just check those only (if those do not have the cancer, than it is much more unlikely for the distant lymph nodes as well). If the sentinel node does have cancer, then the patient may undergo full lymph node removal.

For cost-effective reasons, the evidence does not support every melanoma patient to undergo sentinel lymph node biopsy. Only a very small percentage of early stage patients will have a positive sentinel lymph node – small enough that the costs may outweigh the benefits. Of course, anytime a cost-benefit analysis is done in healthcare, there is controversy. On the other hand, for intermediate stages, there is clear evidence that sentinel lymph node biopsy is useful. For advanced disease, it is currently recommended but does not appear to affect survival – the spread may be too far along at this point.

Radiation may help improve the chance of cure for melanoma, but only in certain cases, and only after surgical removal. The evidence supports its use at the lesion site after surgical removal only if it have particularly aggressive features as seen under the microscope. The same goes for radiation treatment of the neck after lymph node removal if the cancer has aggressive lymph node involvement.

Malignant melanoma is a terrible disease and we all (patients and doctors) need to be vigilant to diagnose and treat it early. Fortunately, many hard-working researchers are continuing to develop a variety of other treatments including vaccines and immunomodulators. As our understanding of the disease improves, so should our treatments.