Precancerous Skin Lesions
Harry Saperstein, MD, FAAD (Dermatologist, Clinical Assoc. Professor, Medicine, Private Practice and UCLA) gives expert video advice on: Is a freckle the same things as a mole?; Can all brown spots such as freckles become cancerous? and more...
Is a freckle the same things as a mole?
There are multiple pigment allesions of the skin, not all of which are nevi, or beauty marks. Two very common pigment allesions are the freckle and what is known as a liver spot, which is really called a lentigo. Freckles are lesions that are occurring in sun-exposed areas, which can occur at a very young age. Those lesions do not have an increased number of pigment cells; there is an increased amount of pigment, however. Lentigos, or liver spots as they're known, are lesions whereby there is an increased number of pigment cells but not grouped in any way and because of that, they are not beauty marks, or nevi. A mole, also known as a nevocellular nevus is a very specific accumulation of pigment cells in the lower part of the epidermis, in the dermis, or in both, and they are significantly different under the microscope.
Can all brown spots such as freckles become cancerous?
Patients present to Dermatologists often with concerns of the little brown spots they see all over their skin, wondering if these can become malignant melanoma or are malignant melanoma. It's important to note that not all brown spots on the skin are moles; there are multiple reasons to have brown spots on the skin. Certainly little kids who have freckles have brown spots. These are not moles whatsoever. Freckles show under the microscope just increased pigmentation. There is no increase of the cells that cause pigmentation called malanocytes. There is a type of brown spot that you see in sun exposed areas, such as on the face and on the hands, known as a lentigo. Lentigos under the microscope will show some increase in the melanocytes, but the melanocytes themselves are not congregated together, which is a finding necessary to make the diagnosis of a mole. Then, there are moles or beauty marks. Thirty per person is the average. These lesions start flat. Some of them are bumps on the skin. Most, if not all, have some pigmentation. Moles, when they become atypical, can become malignant melanoma. It is a difficult thing for a patient to distinguish some of these brown spots on the skin. We understand and empathise but that's why there are experts of the skin to make that differentiation. If there's ever a concern of a changing brown lesion, you should present these to your Dermatologist.
What is "precancer" of the skin?
There are two particular lesions which are considered precancers of the skin. The term precancer is a poor term because something that is a precancer is really going to be a cancer by its definition, and if something's going to be a cancer than it really is an early cancer at that stage. The precancer that goes on to become "scrimsol carcinoma" and perhaps some into "tetrabasic carcinomas" are called actinic keratosis. Actinic keratoses are actually small skin cancers that occur in sun exposed areas on the face and the hands, where there is a red, usually somewhat tender crust that occurs in multiple spots, usually in very fair individuals and over time the actinic keratoses will continue their evolution into a skin cancer. Actinic keratosis is important to find because we can do things to precancers which are less invasive than we have to do when we take care of actual skin cancers. There are also some moles on the skin which are more fragile, or have a greater chance for continuing change. These are not truly precancers, but rather lesions of concern, we do follow those and want to check patients who have these lesions carefully, perhaps as often as 3 times a year, because they have a greater incidence of some of these lesions becoming melanoma, and even some of their normal skin being able to transform itself into melanomas. These patients are at greater risk and should use environmental protection of the highest degree.
What are "dysplastic nevi"?
Dysplastic nevi, which are now more appropriately called clinically atypical nevi, are moles which are not part of the normal size, shape and colouration of the thirty routine moles that patients have in adulthood. They are generally larger than a pencil eraser. They have some irregularity in both colour and shape and stand out in their unusual presentation. It is not uncommon in thirty percent of the population to have one clinically atypical nevus. We do feel that these moles may be more fragile or friable in terms of their predisposition to change. That change is usually a change towards atypicality. There are some patients, however, who have multiple clinically atypical nevi; over twenty-five, in some cases over fifty and even up to a hundred. Those patients are at tremendous risk for developing a malignant melanoma in one of those moles or even in normal skin. There are, in addition to those patients, some families where this is prevalent, known as the B-K mole syndrome or the dysplastic nevus syndrome. Those patients have virtually a hundred percent chance of developing a malignant melanoma in their lifetime if their parents developed a melanoma as well. Those families are rare but we do see them in clinical practice, and we see the patients with multiple atypical nevi relatively frequently in our day-to-day practice of dermatology.