Transcription
Welcome. I'm Andy. In this video, you'll learn what seborrheic keratoses are, who gets them, why do they look the way they do, how to identify them using a dermoscope, and why that matters. And what to do when you find them. And if that's not enough for you, there's a quiz at the end to test you, but also to stretch your learning further, if you feel up to it.
Here's the thing about seborrheic keratoses. We know they are neither sebaceous gland in origin, nor follow the sebaceous gland distribution in the body. So why were they given the name "seborrheic"? It's because in bygone years, before histopathological examination, when palpating their surface, they felt greasy. And that's all. And called "wart" because they sometimes had these keratin fingers projecting up on their surfaces, making them look and feel, well, like a stuck-on wart. However, the name "seborrheic" has stuck.
If you're looking for a more accurate histopathological term, then basal cell papilloma is for you. Use that term if you wish to appear more intelligent at a dinner party, or just want to confuse people, including your colleagues. And as for all you Americans out there, I'll forgive you for getting rid of King George III in 1776, but not for getting rid of the "o" in "seborrheic."
In summary, seborrheic keratosis is the name his mother calls him. Sebk to his acquaintances. Or after you've identified over a thousand, just call him Seb. They are benign, non-infectious proliferations of the basal keratinocytes in the epidermis and unconsidered degenerative in nature. You can't stop someone getting them unless you remove all their skin, and we have laws against that. I hope I feel a graph coming on to explain more.
They are the most common benign skin tumors in humans. The usual onset is considered middle age, but one survey found 12% of 15 to 25-year-olds already had one. Everyone over the age of 60 has at least one. They are equally common in both sexes. Some people have hundreds of them. The one place you'll never find them is on palms, soles of the feet, or mucous membranes. So perhaps not everyone, everywhere, all the time. It just feels like that.
Approximately 1% of people are born with a congenital nevus. Acquired nevi rise to the peak in our mid-20s to 30s. From then on, as we age, the number of nevi plummet due to their disappearance through the process called regression. From a patient's point of view, their moles are changing, but really, what's happening is they are losing their moles and gaining sebks. This is important to realize because any new genuine nevus over the age of 45 to 50 is unusual.
So why do they look the way they do? To help us, I've enlisted a chap to teach us why sebks look the way they do. CHAP is my acronym for four words you need to learn. Write them down. Chant them at meal times, or when doing your yoga, walking the dog, driving to work, or on the toilet. Tattoo them on your knuckles, or if it helps, on your children's foreheads. That last one was a joke, by the way, just to be clear again.
Best explained by way of an illustration. Here's a labeled-up section of normal skin. Let's cook up a sebk. First, we need a little bit of papillomatosis. This is where the dermal papillae rise up above the surface of the skin, resulting in irregular undulations of the epidermis. Next, we have an increase in the number of keratinocytes within the epidermis, causing it to thicken, a process called acanthosis. Remember this term, as around 40% of sebks are called acanthotic.
Now we're cooking. As the process of acanthosis causes a rising and thickening of the epidermis, sometimes it also develops a hard cap, like this particular sebk, with a thickened stratum corneum, a process called hyperkeratosis. Let's not forget the dermal papilla vascular plexus, which grows with the papilla, forming longer hairpin-type blood vessels. The final structure to complete our CHAP are cysts. They are cysts of keratin, some of which are trapped within the thickened, acanthotic epidermis. Many are actually pseudocysts, as in reality, they have a sneaky back door to the surface, unseen on many histological cross-sections. Some of the cysts are very much connected and open out onto the surface.
Knowing this CHAP will certainly help you when we come to explaining features seen on dermoscopy. Here's the histology sections of two sebks. Bright pink is keratin. Guess which one is acanthotic and which is hyperkeratotic. More histology can be found in the video link above, but that's enough histology for me.
How do these four processes explain the variation in how sebks look on the skin? It's because there's a race going on between these four processes occurring at different rates and times, even within the same sebk. Sebks don't just appear fully formed and mature. They start small, grow and mature, and sometimes die by dropping off. I think you are now ready to see if this new CHAP helps you look at sebks in a different light.
First, don't rush to dermoscopy. Spend a little time studying the macroscopic clinical appearance first. Feeling the surface with your patient's consent, and make a guess what you expect to see on dermoscopy. You use dermoscopy to confirm or deny your clinical impression. Take a history. Sebks don't just appear. They grow and change over months, years, even decades. They don't bleed unless traumatized.
Let's now consider the dermoscopic appearance of sebks. What does this in vitro 2D histological CHAP look like when viewed through a dermoscope in the horizontal plane? If you go on a dermoscopy course, you'll be given a diagram like this to explain the dermoscopic features of sebks. Now, this is correct, but what I want to do for you is link the structures you see on dermoscopy to the developmental age and the kind of CHAP the sebk is becoming. You don't see all these features in one sebk. This is a composite diagram. I've given this a name: the four ages of Seb.
In a newborn sebk, the processes that are most at work tend to be papillomatosis and acanthosis. This gives rise to the following. This 63-year-old lady presented to me with this red patch on her left jaw, which she was concerned about. There were many things this could have been, but note the maze-like thin ridges and fissures. This is early papillomatosis and acanthosis. Note the darker line centrally, as the keratin within the tiny fissures has more melanin. She also had this light brown patch on her left cheek. It was macular and looked like a solar lentigo. Some sebks start life as solar lentigines, and this demonstrates well the difference between the fine network of a melanocytic lesion and the thicker, coarser network that are the early ridges and fissures of a baby sebk. I think it's a bit like the difference between the network of a thick chain mail and a fine fishing net. What do you think?
Beside the network pattern for solar lentigines, it can also be homogeneous in color or have a parallel line pattern, as here. Note the white holes of hair follicles and the well-demarcated borders. These parallel lines are often called a fingerprint pattern for some reason.
So what happens as sebks start to grow? As doing a skin survey in this Japanese 40-year-old, I happened to notice this slightly raised, tan-colored plaque on his back. Notice how well demarcated it is, and that the fissures and ridges are thicker and seem better with non-polarized light. Being epidermal in location, this is a growing sebk and not a lentigo or a nevus. In a similar way, on this lady's right cheek, this well-demarcated sebk has a fat finger pattern with the thickened ridges and fissures. The pattern produced is often likened to that of the surface of the brain or cerebriform. Some people call fissures and ridges sulci and gyri for this reason, but the internationally accepted term is now fissures and ridges. This lady was concerned that her mole had got darker, and that was because the keratin in her fissures had been stained by her fake tan that she had had on holiday. This is called the Striae sign.
As the ridges and fissures thicken, cysts of keratin sometimes become trapped in the acanthotic epidermis and shine white on non-polarized dermoscopy, now called milia, after millet seeds. A hybrid dermoscope enables you to toggle from polarized to non-polarized light, and when there are many milia flashing on and off, it's called stars in the night sky. Guy. Sebks can be solitary, but are often in families of all ages, sizes, and colors. Some unfortunate patients have many hundreds of sebks, like this gentleman. But for you and I, our ideal learning ground to look at sebks of different ages and types. This gentleman has quite a few hyperkeratotic sebks. Such a back can appear overwhelming at first glance. How do you pick up a melanoma amongst this lot? While you're looking for the ugly duckling, the one that stands out and is different. And in this gentleman, I found one that was darker and more flat that I wanted to take a closer look at.
Here's the dermoscope. First, note its well-demarcated border, with again the stars in the sky sign of milia flashing on and off. But where the keratin cysts are open on the surface, we have what are now called comedone-like openings, and if large enough, we call them crypts. Also, in immature sebks, the fissures and ridges disappear as the rete ridges fuse into one homogeneous mass. So no fat fingers or cerebriform pattern here. This is a sebk and best left undisturbed. In hyperkeratotic sebks, all you tend to see is scale. This small, mature sebk shows comedone-like openings, many milia-like stars in the sky, and with no large keratin mass covering it, you can see many small hairpin vessels in the acanthotic, thickened epidermis.
Sometimes, for some reason, sebks get irritated, and I call this "angry sebk." He blows his Striae and he gets red in the face. An irritated sebk tends to lose its keratin on the surface, and small hairpin vessels then enlarge. However, hairpin vessels are found in other keratinizing skin lesions, including warts and squamous cell cancers. This gentleman presented with a changing mole on his right scapula for a few months. Can you see any sebk features? An SEC is a possible diagnosis here. So on referral, seare excised it. Histology showed it was an irritated sebk.
Now you understand about cysts, hyperkeratosis, acanthosis, and papillomatosis. With the signs you see on dermoscopy, we can give you a diagram like this. I think this is a good summary of the dermoscopy of seborrheic keratosis.
So why seborrheic keratoses matter? It's because of their variability in color, shape, and morphology. On occasion, they mimic those of a skin cancer, and vice versa. You see, we have this tension. On the one hand, not wanting to over-refer benign sebks as possible cancers. At the same time, trying to avoid falsely reassuring our patients when something looks like a sebk, but in actual fact, is a cancer. Check out this video of mine where with two stories, I explain how we can avoid that outcome in primary care.
What do you do when you find a sebk? Ideally, you do nothing. You reassure your patient, explaining it's a nuisance and unsightly, perhaps giving them a patient leaflet explaining things more. We can't stop them from happening, unfortunately. If you get an income from treating them, lucky you. Here in the UK, we don't provide what is essentially cosmetic surgery without good reason. I do treat them at times using one of the three procedures below, but only when I can justify this for another reason, such as catching on clothing or other irritation symptoms. If you'd like me to produce a video on cryotherapy, just ask me in the comments section below this video.
Sebk quiz clinic time out. If this is your first time learning about sebks, may I suggest you leave this quiz for another time? I just fear it may overload you with too much information and undo some of the good learning you've done so far. Better you go and see your patients and start becoming confident in identifying those dermoscopic features we've mentioned. You can always come back to this quiz another time. This quiz is to stretch those who know sebks already and introduce a few more thoughts and ideas for you.
This 64-year-old gentleman came because his wife had noticed this mole on his left scapula was growing. What features do you see? There's a well-demarcated border, peripheral ridges and fissures giving fat fingers, and perhaps a cerebriform pattern in places. A colleague saw this, and she said that they reminded her of leaf-like structures, which are seen in BCCs, and she's right. They are similar. Both are formed by increased melanin in basal cell keratinocytes. Here, however, there are no other criteria for BCCs and other features pointing away from that diagnosis. See this link in my video on the dermoscopy of BCCs. Note the stars in the sky, milia flashing as I switch from polarized to non-polarized dermoscopy. The central comedone-like keratin cysts are formed in the center, and fusion of the rete ridges centrally gives the homogeneous purplish color. This is a sebk. However, without a dermoscope, it ticks out ABCDE for a melanoma, and many doctors without your skin in dermoscopy would have had to send this for consideration as a possible melanoma. Dermoscopy makes the difference, and the patient was reassured.
This 92-year-old lady came to me wanting this 3 cm soft, fleshy lesion removed from behind her right ear. She'd had it many decades. Sleeping on that side was now uncomfortable. What do you see on dermoscopy? Note the well-demarcated border. Little white and yellow dots are milia, but don't change much between polarized and non-polarized. Here, this is a very mature seborrheic keratosis. You can see the fissures with the keratin, which you might call comedone-like openings or crypts, if you wish. On histology, this was a seborrheic keratosis. I removed it for her using curettage and electric cautery, and two months later, this was the result, with which she was quite happy.
As a bonus, since you've made it this far through the video, our two other patients with very papillomatous sebks, which aren't uncommon. They are soft, pedunculated, and can look similar to a large intradermal nevus. Can you notice the signs giving the diagnosis as a sebk? However, which was the diagnosis on histology.
Patient 3 was an 82-year-old gentleman visiting home to review his resolving chest infection. He asked me to look at his sore shoulder. "While you're here, Doc." Pulling up clothing, I found two ugly ducklings and couldn't resist a look with my dermoscope because I carry it in my bag. Here's a clinical macroscopic view of the lower of the two skin lesions. What do you notice on dermoscopy? Note the three large keratin horns embedded in its surface, and a pink-purple homogeneous color due to acanthosis and a thickened epidermis. Note the many short hairpin vessels and a couple of small milia lighting up without any dermoscopic signs of any other type of skin lesion. I was happy to call this an ultramature sebk.
Now to the upper of the two skin lesions on his back. What do you see on dermoscopy? Did you find any dermoscopic signs suggesting a sebk? No? Well, you'd be correct. This is a barely 0.5 mm deep melanoma, picked up by chance. The patient was unaware it was there. We'll cover melanomas in another video, but just to note, the white orthogonal lines that are on the surface were only seen on polarized dermoscopy.
This 75-year-old gentleman came with a 3-month history of this growing, slightly raised skin lesion on his left cheek. Note the solar lentigines on his sun-damaged skin around it. What do you find on dermoscopy? However, by now, I hope you recognize the well-demarcated edges and the fissures and ridges with a large network-type pattern, much larger and wider than a fine network pattern of an adjacent solar lentigo. There are a few milia flashing on non-polarized dermoscopy, and small hairpin vessels on the pink ridges. This just screams at me, "I'm a sebk, leave me well alone." I hope by now you're doing the same as well.
I was doing another opportunistic full skin survey on this 73-year-old gentleman. This lesion jumped out at me. It ticks some of the ABCD for a potential melanoma, and you now reach for your dermoscope. And find this. What is your diagnosis? And why do you have a dermoscope that only uses polarized light? Then you would have missed these milia lighting up like stars in the night sky. There's a thick network pattern in places with these multiple milia, and no other diagnostic features means this is a sebk. Some will call this a reticular sebk. Another referral saved due to a positive diagnosis being able to be made on dermoscopy.
And finally, patient six. Something that really tested me. This 45-year-old lady actually to a colleague with this lesion on her abdomen, and she said it had been growing for perhaps 6 months. There had been no symptoms otherwise. Macroscopically, there looks to be a small sebk next to it. The lesion itself has a well-demarcated border, stuck-on appearance, some keratin on top, and some small comedone-like structures. Right, sure, it's a little blue and purplish, but some sebks are. I couldn't fit all the lesion on one view for you, so there are five pictures following, helping you working around the edge of the lesion. Pause with each picture and consider what you see. Is this a sebk? If so, why? Are there any features you identify that worry you?
Right, here goes the smaller lesion. I think it's typical for a mature sebk, fissures, and that yellow-brown color. I wasn't worried about this. What about the large lesion? It's got a nice, well-demarcated border. Great. A central keratin mass. Again, not uncommon for hyperkeratotic sebks. There is even some nice comedone-like structures around its pink-purple homogeneous mass. So far, so good. What got me thinking, "Uh-oh," were these. Are these hairpin vessels or linear serpentine vessels? They just didn't look right to me. Then I came to this 3 o'clock section. What stands out to you? This is most un-sebklike. If you watch my BCC video, you recognize this blue-gray color suggesting melanin in the dermis, but sebks are epidermal. What's that doing here? It reminded me of the blue-gray globules or ovoid nests in BCCs or pigmented BCCs, which should then always make you think of a melanoma. I decided it needed cutting out. Two-week wait cancer care pathway due to this finding. However, to make matters more interesting, the patient refused referral. She had anxiety issues, poor experiences of hospital, and was adamant she wouldn't attend. She had capacity and refused to change her mind when we gently explained our concerns. What would you do now? Because my dermoscope is backed up with minor operation skills, she happily agreed for me to remove it that evening for her. I gave it a good excision margin, including that small sebk. What do you think the histology was? Go on, choose one. It was a nodular BCC. That was all it said on the report. Now, I think with the keratin, it's more of a basosquamous cancer. And remember, histology only looks at 1/1000th of the cross-section of a lesion. The small lesion was confirmed as a sebk. So, what this patient taught me was always check all the lesions, don't rush, and always remember, remember the first rule of primary care: dermoscope. If in doubt, refer it out, or as in this case, cut it out.
I really hope you found this video helpful. If so, a thumbs up encourages me to keep making more. If you subscribe, then you won't miss my weekly videos training a primary care. [Music]