Difference Between Moles and Skin Cancer: Key Signs for St. Louis Residents
- Adam Burling
- 16 hours ago
- 14 min read
The fundamental difference between moles and skin cancer boils down to this: moles are typically harmless clusters of pigment-producing cells, while skin cancer is the uncontrolled, abnormal growth of skin cells. Most moles are benign and will never cause a problem, but any change in a mole's appearance is something to take seriously.
Is It a Mole or Skin Cancer? Understanding the Basics
It's a question we hear all the time from our patients across St. Louis, from Ladue to Chesterfield—a new spot has popped up, or an old mole suddenly looks different. Learning what separates a run-of-the-mill mole from a potentially dangerous lesion is the first step you can take toward being proactive about your skin's health.
Most adults have somewhere between 10 and 40 common moles, known in the medical world as nevi. They're simply common growths on the skin, usually brown or black and can appear on all skin types. Skin cancer, on the other hand, develops when DNA mutations trigger skin cells to multiply out of control, forming malignant tumors.
Benign Moles vs. Potential Cancer
While they can sometimes look alike, their biology and potential risk are worlds apart. Melanoma is much rarer than common moles, yet it was responsible for nearly 59,000 deaths globally in 2022. What's surprising to many is that 70–80% of melanomas pop up on seemingly normal skin, not from a pre-existing mole. This statistic, highlighted in research from the Journal of the American Academy of Dermatology in 2017, underscores why paying attention to any new or changing spot is so critical. You can read the full research about these findings for a deeper dive into the numbers.
This visual guide gives a great overview of the basic distinctions.
As you can see, the key visual clues often come down to symmetry and regularity—we'll get into more detail on that shortly.
At Mid-County Dermatology, our board-certified St. Louis dermatologists, Dr. Feigenbaum and Dr. Gibstine, always emphasize that early recognition is your most powerful defense. When you learn the signs, you're empowered to act quickly if something seems off. For a more thorough breakdown, you can learn more about moles in our detailed guide.
Quick Guide: Moles vs. Skin Cancer at a Glance
When you're doing a self-check, it helps to have a quick reference. This table breaks down the most common differences between a typical, harmless mole and a spot that might be skin cancer.
Think of this as your starting point. While it’s a helpful guide, it's no substitute for a professional eye. Any spot that worries you deserves a closer look from a qualified St. Louis skin doctor.
Using the ABCDE Method to Spot Melanoma
One of the most effective tools we teach patients for recognizing the early signs of melanoma is the ABCDE method. It’s a simple acronym that gives you a structured way to look at your moles during a self-exam, helping you pinpoint suspicious features. In fact, our own St. Louis skin specialists at Mid-County Dermatology use these very same principles during initial visual screenings.
Think of it as a checklist for your skin. When you know what to look for, the difference between a normal mole and potential skin cancer becomes much clearer. Let's walk through it.
A is for Asymmetry
A benign, or harmless, mole is usually symmetrical. If you were to draw an imaginary line down the middle, both halves would be mirror images of each other.
An asymmetrical mole, on the other hand, is a warning sign. One half of the spot might be a totally different size or shape than the other, giving it a mismatched or lopsided look.
B is for Border
Take a close look at the edges of your moles. A non-cancerous mole typically has smooth, even, and well-defined borders that you can easily trace with your eye.
Melanoma lesions, however, often have irregular, scalloped, or poorly defined borders. The edges might appear jagged or blurred, almost like they're bleeding into the surrounding skin. This can be a sign of abnormal cell growth.
C is for Color
A single, uniform color is the hallmark of a normal mole. Most are a consistent shade of tan, brown, or black.
A mole with multiple colors is a major red flag. Be on the lookout for a spot that has a variety of shades—like different browns, black, and tan, or even patches of red, white, or blue. This uneven coloring, or variegation, can signal a cancerous change.
D is for Diameter
The size of a mole can also be an important clue. Most harmless moles are smaller than a pencil eraser, which is about 6 millimeters (or roughly 1/4 inch) across.
While some benign moles can certainly be larger, any mole that grows beyond this size should be monitored closely and shown to a dermatologist. This is especially true if the mole is new or has grown recently.
Key Takeaway: While the first four letters are crucial visual cues, the fifth letter is often the most critical indicator that it's time to see a professional.
E is for Evolving
Change is perhaps the most important sign of all. A benign mole will generally look the same year after year, with little to no alteration.
Any mole that changes in size, shape, color, or elevation needs to be evaluated right away. You should also watch for new symptoms like bleeding, itching, or crusting—these are clear signals to schedule an appointment. Performing regular self-checks is a fantastic way to spot these changes early. We offer a comprehensive guide to skin checks for melanoma to help you get started.
Beyond the ABCDEs: Key Symptoms to Watch For
While the ABCDEs are an excellent starting point for visual checks, the difference between moles and skin cancer sometimes comes down to how a spot feels, not just how it looks. A mole that starts to feel different is just as important as one that looks different. Learning to pay attention to these subtle but crucial warning signs is a key part of early detection.
Many patients at our St. Louis dermatology clinic tell us a spot just felt "off" long before they saw any major visual changes. That intuition is powerful. If a mole becomes persistently itchy, tender, or painful without a clear cause like friction from clothing, it absolutely warrants a professional evaluation.
New or Changing Sensations
Think about it: normal, benign moles are typically asymptomatic—you shouldn't even know they're there. When a mole suddenly starts developing new physical sensations, it's a clear signal that something might be changing within its structure.
Here are the key symptoms to be mindful of:
Persistent Itching: A constant itch that is located in or directly around a mole.
Tenderness or Pain: The spot becomes sore when you touch it or develops a dull, constant ache.
Bleeding or Oozing: A mole that bleeds, scabs over, and then repeats that cycle without any injury.
Surface Changes: The mole's texture changes, perhaps becoming scaly, crusty, or bumpy to the touch.
At Mid-County Dermatology, Dr. Feigenbaum and Dr. Gibstine advise patients that any mole that starts demanding your attention—whether through itching, pain, or bleeding—is a mole that needs to be examined by a St. Louis skin doctor.
The Ugly Duckling Sign
Another critical concept that goes beyond the ABCDEs is the "Ugly Duckling" sign. This is a simple but effective way to spot trouble. The idea is that most of your moles probably share a similar appearance, like they belong to a "family" of spots.
A mole that stands out because it's darker, larger, smaller, or just has a different shape is the "ugly duckling." This outlier should be considered suspicious, even if it doesn't perfectly fit the classic ABCDE criteria. It's one of the most practical ways to spot a potential issue. You can learn more about what makes a spot concerning by reading about the key signs of melanoma in our detailed article.
At the end of the day, you know your skin best. If you're in the St. Louis area—from Creve Coeur to Frontenac—and have a spot that seems worrisome for any reason, don't wait. A professional skin check is the most reliable way to get peace of mind and ensure your skin stays healthy.
Understanding Your Personal Skin Cancer Risk Factors
Knowing how to spot the visual differences between a mole and skin cancer is a huge first step. But the other half of the equation is understanding your own personal risk profile. Certain factors can make you more likely to develop skin cancer, which makes regular self-checks and professional screenings that much more critical. When you know your risks, you can take meaningful steps to protect your skin.
Your overall risk is really a mix of your genetics, your environment, and your personal history. Here at Mid-County Dermatology, Dr. Feigenbaum and Dr. Gibstine help patients from Chesterfield to Frontenac figure out their unique situation to create a care plan that makes sense for them.
Hereditary and Genetic Factors
Some risk factors are simply in your DNA. If skin cancer, especially melanoma, runs in your family, your own risk automatically goes up. The same goes for certain physical traits you were born with.
Family History: If a first-degree relative (a parent, sibling, or your child) has had melanoma, it significantly increases your own chances of developing it.
Skin Type: People with fair skin that freckles or burns easily are just more susceptible to sun damage. This applies to all skin types, but those with less melanin have a higher risk.
Eye and Hair Color: Having light-colored eyes (blue or green) and natural red or blonde hair are also linked to a higher risk.
These genetic traits essentially mean your skin has less built-in protection against the UV damage that drives skin cancer.
Environmental and Lifestyle Influences
Your life experiences and daily habits play a massive role in your risk profile. The good news? These are often the factors you have the most control over.
"Your history with the sun is one of the most significant predictors of future skin cancer risk. Every sunburn, especially those during childhood and adolescence, contributes to cumulative skin damage over a lifetime."
The biggest environmental risks include:
History of Sunburns: Just one blistering sunburn can actually double your lifetime risk for melanoma.
Extensive UV Exposure: This isn't just about beach days. It includes long-term sun exposure from working outdoors, hobbies, and—critically—any use of indoor tanning beds. According to the American Academy of Dermatology (AAD), using indoor tanning beds before age 35 can increase your risk of melanoma by a staggering 59%.
Your Skin's Unique Characteristics
Finally, the specific moles on your body are key indicators of your risk level.
Numerous Moles: Having more than 50 common moles is considered a significant risk factor.
Atypical Moles: The presence of dysplastic nevi, also called atypical moles, bumps up your risk, too. These moles can often look a lot like early melanomas, but they are noncancerous.
Understanding these factors is what empowers you to be an effective partner with your St. Louis dermatologist. A knowledgeable St. Louis skin specialist can assess these risks with you and recommend a screening schedule to keep your skin healthy for years to come.
How a St. Louis Dermatologist Diagnoses Skin Cancer
So, you’ve done your skin self-check and found a spot that just doesn’t look right. The next move is to get a professional pair of eyes on it. It’s completely normal to feel a bit anxious about this step, but knowing what’s coming can make the whole process feel much more manageable. Here at Mid-County Dermatology, our job is to make this journey as clear and comfortable as possible for everyone, whether you're coming from Clayton, Creve Coeur, or anywhere else in the St. Louis area.
The first step with a St. Louis skin specialist like Dr. Feigenbaum or Dr. Gibstine is always a detailed visual exam. This isn’t just a quick look—it's a meticulous, head-to-toe inspection of your skin.
The Initial Examination
During your appointment, your dermatologist will likely pull out a special handheld magnifying tool called a dermatoscope. This device shines a light on the skin and allows for a super-detailed view of the structures inside a mole or lesion—things you’d never see with the naked eye. It helps us spot the difference between the orderly patterns of a normal mole and the chaotic, disorganized patterns often seen in skin cancer.
A thorough exam is the bedrock of a solid diagnosis and a crucial part of our expert skin cancer screening services.
The Skin Biopsy Procedure
If a spot looks concerning under the dermatoscope, the definitive next step is a skin biopsy. Don't let the word scare you. It's a quick, minimally invasive procedure we do right here in our St. Louis office. Your dermatologist will numb the area with a local anesthetic, so you'll barely feel a thing, before taking a tiny tissue sample for a closer look.
We typically use one of a few common biopsy methods:
Shave Biopsy: We use a sterile blade to shave off a thin, top layer of the lesion. This is often our go-to for suspected basal cell or squamous cell carcinomas.
Punch Biopsy: A small, circular tool is used to "punch" out a deeper, core sample of the skin. This method is great when we need a full-thickness sample to see what’s happening in the deeper layers.
Excisional Biopsy: The entire mole or lesion is removed with a scalpel, along with a small border of healthy skin around it. This is often the preferred approach for a suspected melanoma.
At Mid-County Dermatology, we know the word "biopsy" can sound serious. But this simple procedure is the only way to know for sure if a spot is cancerous. It’s a vital step toward creating the right treatment plan and giving you peace of mind.
That little tissue sample is then sent off to a dermatopathologist—a specialist who examines it under a microscope to make the final call. This analysis is what truly separates a harmless mole from skin cancer.
Diagnosis and Treatment Path Comparison
Once the biopsy results are back, the path forward becomes crystal clear. What happens next for a benign mole is worlds away from the journey for a cancerous lesion. This table breaks down the typical process for each scenario so you know exactly what to expect.
As you can see, the process is straightforward and designed to get answers quickly and accurately. Whether it turns out to be nothing or something that needs attention, a clear diagnosis is the first step toward healthy skin.
A Proactive Plan for Lifelong Skin Health
Knowing the difference between a harmless mole and something more serious is a great first step, but what really protects you is turning that knowledge into consistent, everyday habits. The best way to approach lifelong skin health is by creating a proactive plan—one that combines your daily routines with expert guidance from a St. Louis dermatologist.
This kind of plan puts you in control. It empowers you to manage the risk factors you can change and spot potential issues at their earliest, most treatable stage. The cornerstones of a solid skin health strategy are simple but incredibly powerful: daily sun protection, regular self-checks, and annual professional screenings.
Master Your Sun Protection Habits
Effective sun protection is your absolute first line of defense. This goes way beyond just slathering on some sunscreen when you head to the pool. It’s a daily commitment to shield your skin from harmful UV radiation, which is the primary driver behind most skin cancers.
Here are the essentials to build into your routine:
Use Broad-Spectrum Sunscreen Daily: Find a sunscreen with an SPF of 30 or higher and make applying it to all exposed skin a part of your morning routine. Don't skip it on cloudy days, either—up to 80% of UV rays can still get through.
Wear Protective Clothing: A wide-brimmed hat, sunglasses, and long-sleeved shirts create a physical barrier that sunscreen just can't replicate.
Seek Shade: Be mindful of when the sun is strongest, which is usually between 10 a.m. and 4 p.m., and try to find some shade whenever you can.
"Your daily habits have the biggest impact on your long-term skin health. A simple routine of sunscreen and sun-smart behaviors is the most effective prevention tool you have." – Dr. Feigenbaum, Mid-County Dermatology
Conduct Monthly Skin Self-Exams
Your next critical task is to become the world's leading expert on your own skin. By doing a monthly self-exam in a well-lit room with a full-length mirror, you can keep a close eye on your skin between professional visits.
Take a mental inventory of all your moles and spots. Pay special attention to any that fit the ABCDE criteria or just seem like an "Ugly Duckling" compared to the others. A great tip is to use your phone to take pictures of certain spots; it makes tracking subtle changes over time much easier. This routine ensures you're the first to know when something new or different appears, giving you the heads-up to call a St. Louis skin specialist for a professional look.
Frequently Asked Questions About Moles and Skin Cancer
Figuring out the difference between a harmless mole and something more serious can naturally lead to a lot of questions. Here, Dr. Feigenbaum and Dr. Gibstine tackle some of the most common concerns we hear from our patients all over the St. Louis area, from Ladue to Chesterfield.
Should I Be Worried About a New Mole in Adulthood?
It's pretty normal for new moles to pop up until you're about 40. But if a new spot appears after that age, it’s a good idea to have a professional take a look.
The research is quite telling: a staggering 70-80% of melanomas show up as brand-new spots on the skin, not from a mole you’ve had for years. This means that keeping an eye out for new growths is just as critical as monitoring your existing moles. A St. Louis skin specialist can quickly tell you if a new spot is benign or needs closer evaluation.
What Is the Most Important Way to Prevent Skin Cancer?
If there's one single thing you can do, it's this: minimize your exposure to ultraviolet (UV) radiation. This isn’t a one-and-done thing; it’s a daily commitment.
Here's what that looks like in practice:
Use Sunscreen Consistently: Get a broad-spectrum sunscreen with an SPF of 30 or higher and make it a part of your daily routine. Every single day.
Wear Protective Gear: Think wide-brimmed hats, sunglasses, and clothing designed to block the sun.
Find Some Shade: Try to stay out of direct sun during the peak hours, which are typically from 10 a.m. to 4 p.m.
Never Use Tanning Beds: Just don't. Indoor tanning dramatically increases your skin cancer risk.
When you combine these habits with regular skin self-checks, you’ve got the best defense possible.
How Often Should I See a Dermatologist for a Skin Check?
As a general rule, the American Academy of Dermatology (AAD) suggests a professional skin cancer screening once a year.
This is especially important for anyone with higher risk factors. That includes a personal or family history of skin cancer, having more than 50 moles, or a past with a lot of sun exposure or sunburns. Here at Mid-County Dermatology, your St. Louis dermatologist will work with you to create a screening schedule that makes sense for your specific risk profile.
Does Having a Mole Removed Mean I Had Cancer?
Not at all. In fact, the vast majority of moles we remove turn out to be completely benign.
Dermatologists remove moles for a number of reasons. Sometimes we do it as a precaution because a mole has some atypical features, and a biopsy is the only way to be 100% sure it’s not cancerous. Other times, a mole might be removed for cosmetic reasons or simply because it’s in a spot where clothing constantly rubs and causes irritation.
If you have a mole or any spot that’s worrying you, don’t put it off. Schedule a professional skin cancer screening with the expert team at Mid-County Dermatology. Book your appointment online today.
This information is for educational purposes only and does not constitute medical advice. Please consult with Dr. Feigenbaum, Dr. Gibstine, or another qualified healthcare provider at Mid-County Dermatology for personalized treatment recommendations. Individual results may vary.