What Are Dysplastic Moles? Opinion and Advice

To better understand the concept of “dysplastic moles,” we must agree on definitions of terms.  Dysplastic from dysplasia  means abnormal development of  tissue.  A mole in this context usually refers to a growth in skin that may be pigmented, flesh-colored, flat or raised, hairy or non-hairy.

Normal pigmented mole on eyelid

A mole, also called a nevus, usually consists of pigment-producing cells  called melanocytes which migrate to the skin where they settle and mature along with the normal skin cells.  Interestingly, melanocytes are derived from nerve tissue in the developing embryo, and not from primordial skin cells.

Moles may be present at birth, called congenital, but most are acquired during a lifetime.  It is normal to have moles.  The average Caucasian adult has about 40 moles.  New moles may appear at any age, but their growth tends to fall off by age 40 years.  After that, some moles may actually get smaller, lighter in color, or disappear completely.  Less commonly, a pigmented mole develops a white ring around it and gradually fades away.  This phenomenon is called a “halo nevus,” and these are almost always harmless.

The concept of dysplasia in moles has been around for decades, with the understanding that some moles may transform into malignant melanomas.  However, from studies of biopsy material, we know that most melanomas arise from normal-appearing skin.  Some arise from congenital moles

Congenital moles are present at birth. They tend to be large and hairy and enlarge as the individual grows.

where the risk is higher when these moles are very large, sometimes covering an entire extremity or segment of the body.  Some melanomas arise from previously normal-appearing moles, and still others arise from abnormal or dysplastic-appearing moles.

During my 30+ years in the specialty of dermatology, I have followed the evolution of the “dysplasia” concept starting with the reports of the Familial Atypical Mole and Melanoma syndrome by Lynch in 1978, whereby patients and their first degree relatives demonstrated many large and bizarre-appearing moles on their trunks.  These patients had a very high risk of developing melanoma, approaching 100%.  Subsequently, these patients were determined to have the Familial Dysplastic Nevus Syndrome by Clark and others.  It was then noted by astute investigators  such as Al Kopf and his disciples that many persons, perhaps all Caucasians, had one or more dysplastic moles on their bodies whether or not they had a personal or family history of melanoma.  These patients were then said to have Sporadic Dysplastic Nevi (Moles).

The clinical description of dysplastic moles is that they tend to be large, irregular in outline, and have different colors within them.  A typical example is one that looks like a

This dysplastic mole has the typical “fried egg appearance” described in the text.

fried egg with a dark brown color in the center and a lighter brown or red around it.  The problem is of course that this description may also apply to many melanomas.  Then how do you tell them apart?  The best way is by skin biopsy or complete surgical removal.  There is also another method of direct microscopy on the skin surface with an instrument called the dermatoscope which is similar to an ophthalmoscope.  A computerized system which scans the mole and compares all of its features to thousands of  moles and melanomas which it has previously learned and which were confirmed by biopsy has been developed by Harold Rabinovitz, Darrell Rigel, and others.  This device, called Melafind, is now available for purchase.  The inventors recommend that it be employed for scanning suspicious pigmented lesions to help decide whether a biopsy should be done rather than screening all pigmented moles randomly.

One of my mentors, and perhaps the most innovative dermatopathologist in the last century, was A. Bernard Ackerman.  Everyone called him Bernie.  Bernie had a different opinion about the so-called dysplastic mole.  He agreed that they existed, but he also believed that their distinctive features under the microscope made them the most common mole of humans.  He called them Clark’s nevus in what was perhaps ironic tribute.

In current dermatological practice, when we see a mole which shows features of the ABCD’s, that is, Asymmetry, Border irregularity, Color variegation, and Diameter larger than a pencil eraser, we think of melanoma and perform a biopsy.  What if the person has 10 of these, or 20, or 100?  Do you remove them all?  Of course that is not practical.  You can biopsy a few of the most abnormal appearing moles.  When these are examined under the microscope by the dermatopathologist, she will grade the atypical appearance of individual melanocytes as mild, moderate, or severe and report whether the entire mole was removed by the procedure.  If the mole was not entirely removed by the biopsy, then it is prudent to go back and perform a conservative re-excison of the biopsy site.  The reason for this is that some authorities consider a dysplastic nevus a precursor of melanoma while others believe that it is merely a marker for a higher risk for developing melanoma in a lifetime anywhere else on the body.  Both camps agree that the risk is greater for the more severely atypical cells and that such patients should perform self skin exams regularly and have a full body skin exam at least annually by a dermatologist.

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4 Responses to What Are Dysplastic Moles? Opinion and Advice

  1. Mia Boyd says:

    Thanks for the information. To be honest, the first time I heard the word dysplastic was today in my dermatologist’s office. He said that I’ve got three dysplastic moles. That means they’re cancerous, right? It seems to me like I’ll be needing to start some skin cancer treatment.

    • DrCamisa says:

      Dysplastic moles are NOT cancerous. They do contain abnormal cells that increase the chance of the mole transforming into a melanoma. At worst, they might be considered “pre-cancerous.” They can be cured by complete local excision. Your dermatologist will be able to explain why he is going to remove them or just follow them. Our skin pathologist recommends excising moles that show moderate to severe dysplasia. It’s probably safe to measure, photograph, and follow the mild ones for changes.

  2. Rlukas says:

    I just had a mole removed that had some previous trauma. I burned it with nair. Bad enough to the point where it went from light brown to bright red. It even ruptured the area in the mole.

    Fast forward 17 months I had it removed. It healed with a somewhat red center, overlaying where it was ruptured and light brown around it. It never changed in size nor shape.

    To my surprise the pathology report said it was severely atypical. Could that trauma have played a role in the cytology and architecture of that mole?

    I’m getting the area excised on Tuesday. This will be my second severe atypical mole removed in the last 6 years. Should I be worried? I have no more atypical moles. I had 5 other mild ones removed as well. My derm still believes once a year visit is all I need.

    • DrCamisa says:

      It’s reasonable to speculate that trauma to the mole may have contributed to the severity of the dysplasia. In any case, it is appropriate to excise it with clear margins as you are doing.Because you have had several other dysplastic moles, you may have a genetic tendency to develop these. In addition to the annual visit, you should call the dermatologist if you develop new moles or changes in old ones that are suspicious or remind you of the previous dysplastic moles, especially the severe ones.

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