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Clinical Manifestation and Differential Diagnosis of Acne


Dermatology experts comment on the clinical manifestation of acne and the importance of differential diagnosis.

Hilary E. Baldwin, MD: Fran, anything to add on the clinical manifestations of acne that you see in your practice?

Fran E. Cook-Bolden, MD: Julie gave a great review of the clinical manifestations of acne. We have comedones, which can be whiteheads or blackheads. That depicts whether they’re open or closed. The open comedones are oxidized, which turns them black, and that’s why we call them blackheads. We then have papules and pustules. If there’s pus in them, then we call them pustules. Some people refer to papules as pimples. When the inflammation and swelling are deep in the skin, then a nodule or cyst can develop. The nodule is solid, and the cyst is filled with sebum or pus, but both are tender. There are different forms of acne. Acne mechanica is from friction or rubbing, which we see in athletes. We also see it from anything: wearing a cap or a hat on a regular basis can cause the acne mechanica, or even a scarf.

Then there are your more severe forms of acne, such as acne conglobata and other severe forms of acne where you primarily have nodule, cysts, and scarring with the connected channels underneath the skin. When we talk about acne, we’re most commonly classifying it as mild, moderate, or severe when we are talking to our patients and in general conversation. When we’re doing research on acne, we include that almost clear category or that clear category when acne is totally resolved. Those are the most common forms that we see.

James Q. Del Rosso, DO: I’d like to add something though. I’m glad Fran mentioned the mild, moderate, and severe cases. The fact is that, when we’re seeing patients, we’re seeing them in a small snapshot of time. I’m talking about in clinical practice, not in research.

Fran E. Cook-Bolden, MD: Correct.

James Q. Del Rosso, DO: We’re looking at the patient on that day, but unless they have acne at the far end and couldn’t get much more severe, if they’re in the middle, I always magnify that by 25% or 30% because I may not be seeing them on the day that it’s at its worst. If I only treat what I’m seeing on that day, I’m probably going to be chasing from behind. Is it OK if I ask a question, Hilary?

Hilary E. Baldwin, MD: Absolutely, go ahead. Fire away.

James Q. Del Rosso, DO: I still see patients who come in who were going to another dermatologist, and I never like to be thinking, “What the heck was that person thinking with this?” I’m sure people are sometimes saying that about me when one of my patients goes to somebody else. When the patient has a diagnosis of acne, and you go into the room, and you go, “I don’t think this is acne; I think this is rosacea.” I see that, and I don’t want to say that it’s all the time, but I see it more so than I would expect to. Are you noticing that?

Hilary E. Baldwin, MD: Yes, I see that quite frequently, and I walk in the door, and I’m thinking, “I’m sitting down to have a rosacea conversation,” and I find out that I’m sitting down to have an acne conversation. I see that quite frequently, and when it comes from a PCP [primary care provider], I’m not terribly surprised. I’m surprised when it comes from a dermatologist. What about you all? Do you see that too?

James Q. Del Rosso, DO: I’m surprised, but I also don’t know what it looked like when they went to the other doctor.

Hilary E. Baldwin, MD: That’s a good point because it does change over time.

Julie C. Harper, MD: That would have been what I would have added. I’m glad that my Alabama patients aren’t going out to Nevada to see you Dr Del Rosso.

If I’m honest, I’ve had patients like that, where I’ve seen them at 1 visit and thought, “This is rosacea,” but then I see them at a subsequent visit and say, “You know what, there is now this component of acne as well.” Those things can coexist. I know that doesn’t happen often, but there are times where my charts talk about an overlap between those.

Fran E. Cook-Bolden, MD: That’s possible because, with acne, you can sometimes manifest with just mostly inflammatory papules. It can look just like rosacea with few comedones, and the next time they come in, just like you said, you then see more lesions that are consistent with a diagnosis of acne. It depends on what we’ve all said: what the provider saw when they saw them at that point in time.

Hilary E. Baldwin, MD: Yes. That’s especially true for darker skinned patients where the erythema might have been overlooked. You see the papules and say, “This is acne,” without going further and asking about symptomatology. “Is it burning and stinging? Do you feel hot to the touch?” There are also ocular changes and other things that may be present in a patient with rosacea.

Julie C. Harper, MD: This whole conversation reminds me of something you said a long time ago, Hilary. This is one of the most memorable stories in my dermatology career.

Hilary E. Baldwin, MD: Uh oh.

Julie C. Harper, MD: You’re going to know exactly what I’m talking about. Something we’re talking we’re talking about here is examining patients. We can sometimes be so quick about that because this is a diagnosis that we can make from across the room 95% of the time. There was an old survey done that showed that our patients sometimes feel like we’re not looking at them closely enough. Dr Hilary Baldwin is sneaky, so after hearing that, she would say that she would take her magnifying glass. She wants to build the confidence of the patient, so she would take the magnifying glass and get very close to the patient, and that makes them feel like we’re looking closely, and of course we are. The rest of the story, Hilary, was that you would be planning your dinner for that night or something like that when you did it.

Hilary E. Baldwin, MD: Yes; 10 full seconds of thinking about what I was going to cook for dinner that night.

Julie C. Harper, MD: We don’t always have time to think about that either, but we do want to be sure we’re examining the patient. As we all know, the comedonal acne is the key finding. Most of the time, we’re going to see it. We know that the ratio between comedonal and inflammatory acne shifts over time. Our youngest patients are mostly comedonal: they have acne in the T-zone, they have them in their ears, and then over time, that shifts. With our adult female patients, you’d sometimes have to hunt pretty hard to find a comedonal lesion. They may have shifted more to where they have inflammatory lesions.

To Jim’s point, that adult woman sometimes comes in, and on the day she sees you, she doesn’t have any. She’ll tell you, “If you would have seen me last week, I had 2 huge knots on my chin.” We have to look closely, and we have to take a good history.

There are other things that can mimic acne, other than rosacea, which can definitely mimic acne, but you should look for the comedones. It can sometimes be perioral dermatitis when we have that lower face involvement. Granulomatous rosacea could look like acne, and pityrosporum folliculitis could as well. None of these are perfect. Lupus miliaris disseminatus faciei could as well. These are things that could look somewhat like acne.

I’ll say another thing that I see every now and then: true epidermoid cysts. Somebody comes in who has been on isotretinoin for a long time, and they won’t stop it because they have 3 lesions that won’t go away. When you look and examine more closely, those lesions are not going away unless we excise them.

James Q. Del Rosso, DO: On the subject of examinations, we have to recognize that, if we don’t ask to look at the trunk, we’re not going to be told.

Julie C. Harper, MD: That’s true.

James Q. Del Rosso, DO: Many of these patients have truncal acne, and the severity is discordant. It could be severe on the face, mild on the chest, moderate on the back. The idea is that it’s far more common in men than women, but we know that’s not true. A lot of the time, they don’t necessarily tell us about truncal acne. We have to ask to be able to examine their chest, back, and shoulders, or else we won’t know about it.

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