Transcription
I was thinking the other day, one of our aims as Primary Care dermatologists is our patients becoming like Swiss cheeses. No, not fermented and covered in wax, however tempting that may be at times, rather full of unnecessary holes in their skin from the excision of benign, non-cancerous skin lesions that were really best left alone.
Now, you might not have realized it yet, but you have a problem to solve. It's called the patient with the pink papule problem. Let me show you a patient to illustrate what I mean. This 67-year-old gentleman presented to me with this pink papule on his left thigh. It was 5 mm, firm to touch. What is it? You see, pink papules like this have a long list of possible causes, from the benign to the malignant nasties.
Which brings us to this week's topic, which is dermatofibromas, because they are one of the possible answers to solve your PPP. Patients with a pink papule problem. Oh, hang on a minute, I think I have to pee. Um, excuse me a minute. Ah, that's better.
How are you going to tell if this papule is benign, or if it's a nasty that needs the services of a Swiss cheese maker? Did I hear you whisper a dermoscope? You're correct, but don't rush to dermoscopy. Consider your patient's risk factors for skin cancer to identify those high-risk individuals. This changes the probability of that papule being a problem.
What's the first question then, you want to know about this problematic pink papule? If your answer was, "How long has it been there?" you're close, but not close enough. Why? Because what you actually want to ascertain is its growth trajectory. You see, benign conditions, such as dermatofibroma, sometimes appear quickly over weeks and months, but then remain static or change slowly over decades. Cancers do what cancers do: they grow and keep on growing.
Patients' recollection of time often isn't very good, so try these questions, which I find more useful. "When did you first notice it?" "What did it look like then?" I find these two questions much better than the generic "How long has it been there?" question. "How has it changed between then and now?" This will give you a better feel for its growth trajectory.
What are dermatofibromas? The clues are in the name. Dermato means of the skin. Fibro, fibrous scar tissue in the papillary dermis, to be precise. And oma, meaning tumor or swelling, giving us dermatofibroma. Cause unknown, although thought to be triggered perhaps by some minor skin trauma, such as a puncture wound, mosquito bite, or ingrown hair. They are more common on the exposed surfaces of the arms and legs, but it's not uncommon to find them on the trunk. The male to female ratio is 4 to 1 for some reason, and they range in size, usually 5 to 10 mm, but can be 2 to 20 mm. The color is variable: pink, but tan, blue, brown is also possible.
So, you've asked your questions about your patient and the pink papule. What's the next thing you want to do? Just put that dermoscope down a moment longer. You need to touch and feel the papule. Is it soft like an intradermal nevus? Classically, a dermatofibroma will be firm and hard. That's because it's scar tissue, after all. But also, that scarring in the center means that the center is tethered. And by pressing it from both sides, the center that dimples downwards. And this is called the pinch or dimple test.
Now, I don't have a positive predictive value for this test, but if it can help sway you towards your PPP being a dermatofibroma, now you can get out your dermoscope. How would you describe this? I think it looks a bit like a star exploding. The two key features of a classic dermatofibroma are here. There should be a central white patch. Note that this center should be paler than the surrounding skin. But also, a fine network pattern which fades out at the edges.
Hold on a minute, I hear you say, "Isn't a pigment network one of the main criteria to tell us that it's a melanocytic lesion?" And you'd be right. But dermatofibromas are an exception to the rule. Why can't life be simple? The pigment network, however, formed in a dermatofibroma, is due to hyperpigmentation within the basal keratinocytes along the basement membrane, as opposed to melanin within Kni cells along the basement membrane in a Kni or mole. It's easy to miss with a cheap dermoscope using a phone camera to capture an image if you're not looking out for it.
Let's look at the dermoscopy of this lady with a PPP on her arm, which was dimple positive. We have a central white patch again, with shiny white structures, which is your scar collagen, which flashes on and off under polarized and non-polarized light. This is the altered collagen in the dermal papilla, best seen on polarized dermoscopy. And up to 75% of dermatofibromas will have this radial pattern of a fine network plus a few vessels in the central white patch. Vascular patterns vary in dermatofibromas and are non-specific, and include dotted, comma, hairpin, glomerular, linear, and any combination. Some have no vascular structures at all visible. Some are made up of just vascular structures. And others, like here, are patchy.
For this lady, her PPP hadn't changed in 5 years, and I was confident to give her a diagnosis of dermatofibroma and reassure her strongly with appropriate safety netting. No Swiss cheese maker for her. One-third of dermatofibromas are of this classic pattern. However, there are 10 to 15 subtypes recognized, some of which can't be reliably differentiated from a melanoma. Why? Because at times, some of the features are similar between a dermatofibroma and a melanoma, in particular pigment network, shiny white structures, and variable vascular structure.
Can you treat dermatofibromas with cryotherapy? I wouldn't. Unlike warts and seborrheic keratoses, which are just epidermal in location, dermatofibromas are dermal, and you'll just likely cause more scarring. If they do need treating, mainly because of diagnostic uncertainty, they actually need excision biopsy.
I think I've now prepared you to test and stretch you a bit more with my PPP P P. How many P's was that? Five patients with a pink papule problem. In a quiz, not all of them are dermatofibromas. And if they aren't, what are they? Can you tell me before I tell you? And if you're finding value in this video, please bump that thumbs up button to encourage me to keep making more videos like this.
This 46-year-old lady came to see me when I was working a shift at the GP out of hours. She didn't come about this pink papule on her arm, but I noticed it. Question: What's the difference between a soldier and a civilian? One runs towards gunfire, the other away from it. I think it's a bit like that with a GP dermatologist. Do you run away or towards it? She noticed it perhaps 5 years ago, and in the time between then and now, it hadn't changed at all.
What do you see on dermoscope? It's symmetrical with a clear central white patch with some shiny white structures, more prominent on polarized dermoscopy. There's a faint pigment network around the periphery, but little in the way of vessels present. This, I hope you now recognize, is a classic dermatofibroma.
This 41-year-old gentleman came to me with a pink papule on his right calf. He'd noticed it 2 years previously, and it hadn't grown since then, but he felt it had become more red, so came to get it checked out, just to be sure. Note how the center blanches on pressure, and his pinch test negative, despite my best efforts. First, note the symmetry of the structures, which is reassuring. A pink center with dot and perhaps short hairpin vessels. However, added to this mix are many white orthogonal lines, showing up best on polarized dermoscopy, i.e., shiny white structures. There's a tan-colored faint network around the periphery, fading out at the edge. This is still a dermatofibroma. The shiny white structures are more organized this time. The vessels give it its red, blanching quality. I reassured him, and it's remained unchanged over the last 2 years.
This 43-year-old lady came with this pink patch on her left shin, which she noticed slowly appearing over the previous 6 months. It had bled once, which she assumed was due to her using a razor on her legs. It was 5 to 6 mm in diameter, slightly raised, pink, and pinch test negative. Press. Look at these photos and list all the structures you can see, and decide if you think this is a dermatofibroma or not. There are no central white patches, but certainly some blotchy shiny white structures seen only on polarized dermoscopy. A yellow-brown erosion, or perhaps trauma from her shaving. A homogenous pink background, but no network around the periphery. The vascular aspect shows perhaps a few knotted vessels here, perhaps some hairpin type, and an odd structure here. I wasn't convinced this was a dermatofibroma, and the shiny white structures, or as I call them, "star worrying structures," made me concerned that it might be a BCC or melanoma. With this uncertainty in mind, it needed referring for a second opinion. But she was happy, after a discussion, for me to do an excision biopsy, which showed, well, you choose what you think it is. Histology showed it was a BCC with both superficial and nodular elements, completely excised. If you haven't watched my BCC video, follow this link, and you'll see why it fits best with a BCC.
This 78-year-old lady came with this bluish-purple, 7 mm papule around her left ankle. She had first noticed it around 2 to 3 years ago, and it hadn't particularly changed in size recently, but had started to itch, which prompted her to attend. What do you make of the dermoscope? Describe what you see. It's symmetrical in pattern and features. Over a central purplish area are blue-white shiny structures, which did show up better on polarized dermoscopy, surrounded by dots or small coiled vessels around the periphery. What do you think it is? I wasn't completely sure, but had a hunch, which isn't enough when shiny white structures are involved. So I sent the photographs to telederm to see what they thought. They weren't sure either, so they excised it, and it was, drum roll please, a dermatofibroma. Remember, there's a range of subtypes of dermatofibromas, and in the comment section, you'll find a link to an article which will go into this in more detail. However, your primary purpose initially is to recognize the regular, classic dermatofibroma rather than these unusual subtypes.
This 51-year-old presented with a 12-month history of his slowly enlarging tan-pink colored papule on his left lateral thigh. It was slightly raised, oval in nature, particularly with the pinkish area at the 3 o'clock side. A previous mole removal from his back had been benign, but he thought his mum may have had a melanoma, and on checking his skin generally, I noticed he had more than 50 nevi, a few of which looked misshapen. Have a look at the dermoscopy and see if you can decipher the features of dermatofibroma. H. What do you think? It's not symmetrical, but there are lots of hairs coming out of it, which must be reassuring, right? A pink-white bit at 3 o'clock. I can't see any shiny white structures. There are small red dots within a homogenous tan periphery. A few things made me nervous here, and I hope you as well. First is the gradual change in this skin lesion. It's growing. He has maybe a first-degree relative with melanoma, increasing his personal risk, as does having more than 50 genuine moles. He may be one of those high-risk individuals for a melanoma. Also, I couldn't positively identify this lesion as benign, certainly not like any of the dermatofibromas we've seen so far. The first rule of primary care dermoscopy: if in doubt, refer it. Which I did, as a two-week cancer care pathway referral. Histology showed it was an in situ melanoma. I showed the photos of this lesion to a colleague who said, "Andy, how did you know it was a melanoma?" The answer to which, I hope you now understand, I didn't. But I couldn't reassure myself it was benign. And if you haven't watched my video with two stories explaining this principle of how to avoid missing a melanoma, click this here.
Remember the beginning of our journey in this video? In this chapter, a patient with a PPP on his thigh. Well, here's the dermoscope. Can you make a sense of it now? It's symmetrical, and dermoscopy shows the white center with shiny white structures and small dotted and coiled vessels around the center. It was pinch positive, which helped to reassure me it was just a dermatofibroma after all. Another patient saved from becoming Swiss cheese. To become that great Primary Care dermatologist is a dermatofibroma, starting with the classic pattern: a central white patch surrounded by the fading network pattern with a positive pinch test. Learn to do that confidently. Until next week's episode. Nanu nanu. Training a primary care dermatologist for every general practice.