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Benign Nevus and Dysplastic Nevus

by Carlo Raj, MD
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    00:01 Our topic now brings us into nevi.

    00:04 So with nevi, what we’ll do is first define what a nevus is.

    00:08 Nevus is a cluster of melanocytes.

    00:11 Once again, a nevus is a cluster of melanocytes.

    00:15 If it’s cluster of melanocytes, then guess what color it’s going to give your skin.

    00:19 Well, depending as to location.

    00:22 By that I mean, if it’s in the epidermis more so, then it will give your skin a pigmented or brownish type of appearance.

    00:29 But if you have a cluster of melanocytes that is deeper down in your dermis, well, think about that please.

    00:34 If your melanocytes are deeper down in the dermis, how was that then going to give you -- or the presentation of such significant hyperpigmentation? And really, it doesn’t.

    00:44 But at this point, all I’m going to introduce you to is the definition, which is cluster of melanocytes.

    00:51 We’ll first walk through our benign nevi.

    00:53 And once we walk through our benign nevi, then what may then happen to the nucleus is the fact that it may then become atypical.

    01:01 And if you have an atypical or dysplastic nevi, guess where we're headed? Our third, well not really third, but another type of skin cancer known as your melanoma that obviously that being extremely common in the U.S.

    01:16 There are two categories.

    01:17 The common nevus which is symmetric, uniform without atypia.

    01:22 What does that mean to you? Benign, benign, benign, benign, benign, right? We’ve had the discussion plenty in neoplasia.

    01:28 Without increased concern.

    01:32 If on the other end of the spectrum, we have a nevus that is dysplastic.

    01:37 Irregular shape, pigmentation with atypical cytology.

    01:44 Possibly preneoplastic, hence, it requires and mandates and warrants proper followup to make sure that your patient doesn’t go into melanoma.

    01:53 Is this understood? Lay down the foundation first for nevi, it is only then that you’re permitted to move on to our various steps to nevi and then eventually into our melanomas.

    02:07 Benign nevus, junctional is our first description.

    02:12 I’m not going to give you a picture for every single one.

    02:14 Where it’s necessary, I’m going to give you a high-yield picture.

    02:17 But at this point, I would like for you to think about the definition or the concept of junctional.

    02:23 Where are you right now? You’re on the skin.

    02:25 And so therefore, the major junction that you’re thinking about is your dermoepidermal junction.

    02:31 So at that particular junction, at the DEJ, there is a macular lesion.

    02:36 Macular, what does that mean to you? You can’t really feel it.

    02:39 Composed of? Well, what does a nevus mean? A cluster of melanocytes.

    02:43 There you go.

    02:44 And so therefore, you’re going to find a hyperpigmented type of presentation.

    02:51 Compound.

    02:52 Now as we move from the junctional, we’re going to start talking about nevi or clusters of melanocytes which are then going to invade deeper.

    03:00 But keep in mind, that we still are not referring to dysplastic nevus.

    03:05 Not yet.

    03:06 So compound nevus will be a papular lesion, once again, which now is going to extend further down into dermis.

    03:15 And finally we are in only the dermis, intradermal.

    03:20 So if we think intradermal nevus, we were talking about these clusters of melanocytes that are now strictly in the dermis.

    03:28 Therefore now, this particular papule minimally if at all pigmented.

    03:32 Is that clear? Why? Because the cluster of melanocytes is not as superficial as it was with intradermal.

    03:39 I would like for you to create a story for yourself as we’re moving from the junction into the compound, from the compound strictly into the dermal.

    03:49 Is this clear? All referring to nevi of different types and clusters of your melanocytes.

    03:58 If you take a look at this intradermal nevus, granted, it looks a little pigmented, but truly, In terms of its color, it really is an extension of the natural complexion of your patient.

    04:14 Where is the cluster of nevi here? Strictly in the dermis, intradermal.

    04:22 Here, we take a look at dysplastic nevus.

    04:24 Usually sporadic.

    04:26 And how dangerous is dysplastic? Really dangerous.

    04:29 Dysplastic nevus syndrome, inherited disorder.

    04:33 D-N-S, dysplastic nevus syndrome.

    04:37 You must think of it as being premalignant thus warrants proper follow up because you’re worried about melanoma.

    04:47 With dysplastic, here is your A through E criteria.

    04:51 A, B, C, D, E criteria for being concerned or being highly concerned about neoplastic changes.

    05:02 If you’re able to meet some of the criteria here or A through E criteria for a nevus, you’re that much closer to melanoma.

    05:12 I’ll show you.

    05:14 Asymmetry.

    05:15 Border irregularity.

    05:16 C – color variegated, many colors within the same nevus.

    05:20 Diameter, memorize greater than 6 millimeters of the nevus.

    05:26 And evolution.

    05:29 If A through E criteria had been met, you’re increasing risk for melanoma.

    05:38 Dysplastic nevus.

    05:40 If you were to then take a look at this, it’s utter chaos that is taking place.

    05:44 It’s difficult to actually identify the epidermis or dermis.

    05:48 And as far as the cells are concerned, melanocytes, they’re undergoing atypical changes.

    05:54 You see this here on your histologic section.

    06:00 Now with nevi, differential diagnoses: We’ll talk about melanoma.

    06:05 As soon as you hear about seborrheic keratosis, you’re thinking about what? Stuck on appearance, older patient, autosomal dominant, slowly growing, more likely containing pigment.

    06:14 A cherry hemangioma, this is a small dome shaped bright red papule.

    06:20 Increased number with age and remember that it’s permanent, very common and extremely benign.

    06:25 A cherry hemangioma, it looks like a cherry.

    06:28 Think of a cherry for me and that’s exactly what a cherry hemangioma looks like.

    06:33 These are differentials for nevi.

    06:38 Here, we’ll take a look at a clinical benign nevus.

    06:42 This is what’s known as a junctional nevus.

    06:46 A junctional nevus would be located where? Clusters of your melanocytes between the dermoepidermal junction.

    06:53 And therefore, because it’s a little bit more superficial, you will then give this presentation of being, well, symmetrical.

    07:02 The border is nice and well demarcated.

    07:05 The color, homogeneously dark.

    07:09 The diameter, less than 6 millimeters.

    07:11 Trust me on that.

    07:13 And there is no elevation.

    07:14 This is a macule.

    07:15 What did I just walk you through? A, B, C, D, E versus clinically atypical nevus.

    07:26 Start with A, asymmetrical.

    07:29 B, irregular border.

    07:33 I want you to compare here on the right to your left.

    07:36 C, look at the central portion of the nevus.

    07:39 It is dark.

    07:41 The peripheral portion is lighter.

    07:43 So different colors.

    07:45 D, the diameter is greater than 6 millimeters compared to diameter here on your right to the one of junctional nevus on the left.

    07:54 E, it’s elevated.

    07:58 Macule on the left and elevated type of lesion on the right.

    08:03 You see something like this in A through E or suspects or fulfills the criteria of A, B, C, D, E, You’re worried about what? Going on to melanoma.


    About the Lecture

    The lecture Benign Nevus and Dysplastic Nevus by Carlo Raj, MD is from the course Neoplastic Skin Diseases. It contains the following chapters:

    • Benign Nevi and Dysplastic Nevi
    • Benign Nevus
    • Nevocellular Nevus
    • Dysplastic Nevus
    • Nevi

    Included Quiz Questions

    1. Melanoma
    2. Benign nevus
    3. Compound nevus
    4. Eczema
    5. Atopic dermatitis
    1. Cherry hemangioma
    2. Strawberry hemangioma
    3. Port-wine stain
    4. Pyogenic granuloma
    5. Skin tag
    1. Dermoepidermal junction
    2. Epidermis
    3. Dermis
    4. Hypodermis
    5. Stratum lucidum
    1. It is an autosomal recessive disease
    2. The lesions slowly grow over time
    3. It is an autosomal dominant disease
    4. It is mostly seen in older patient
    5. The disease always has pigmented lesions

    Author of lecture Benign Nevus and Dysplastic Nevus

     Carlo Raj, MD

    Carlo Raj, MD


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