'What Are These Bumps I See All Over?'

Dermatology for the Primary Care Clinician

Charles P. Vega, MD; Temitayo A. Ogunleye, MD


March 22, 2018

Charles P. Vega, MD: A 55-year-old woman comes to see her primary care physician with a chief complaint of "What are all these bumps I see all over?" She has noted an increasing number of asymptomatic, small yellow and red papules on her buttocks and around her knees. She has no new chemical or other exposures. She reports nothing new in her life.

Her medical history includes gestational diabetes and hypertriglyceridemia. That worries me. In fact, the patient was treated with a fibrate years ago, but then another physician told her to stop because it would not help her risk for cardiovascular disease. She is obese, with a body mass index of 40 kg/m2. She also has some menopausal symptoms, mostly hot flashes, for which she takes combined estrogen/progesterone. She also takes fish oil, calcium, and vitamin D.

This photograph highlights what the papules look like. Tayo, tell me what you're thinking.

Figure 1. Monomorphous, yellow/red papules.

Temitayo A. Ogunleye, MD: My first bit of advice is to think about the distribution, color, and size of the lesions. I think some important variables in this case are that the areas of involvement for this patient are on the buttocks and around the knees. It is also important to consider the time over which the lesions have appeared. Because they have just appeared, over several days, they have an eruptive nature. The fact that they have a yellow/orange undertone is something that is important to think about as well.

Small yellow/orange papules on the buttocks and extensor surfaces that appear over a short period make me think primarily about eruptive xanthomas.

Dr Vega: What's the differential diagnosis in this situation? I don't think that many primary care physicians will see this type of lesion, although they should be able to spot it now if it comes in. Knowing what is on a differential here is critical.

Dr Ogunleye: I agree. The differential is critical because eruptive xanthomas are not a common diagnosis, although once you know their distinguishing characteristics, it can be an easier diagnosis. I don't even think that a lot of dermatologists have seen it that frequently, although we all learn about these types of things.

A more common diagnosis to consider may be molluscum contagiosum, because of the dome-shaped appearance of these lesions. Another diagnosis to consider may be sarcoidosis, although sarcoidal lesions typically have more of a reddish-brown undertone (Figure 2), and potentially a wider breadth of possible clinical presentations.

Figure 2. Reddish-brown papules seen in a patient with cutaneous sarcoidosis.

Dr Ogunleye: If you have a patient who presents with diffuse papules in this distribution, one of the distinguishing variables is color. Yellow/orange-red papules should make you think of cholesterol or fat, and the dome-shaped appearance, distribution on extensor surfaces, and eruptive nature may help seal the diagnosis. Sarcoidosis or other granulomatous lesions may be more reddish-brown, will rarely occur in an eruptive fashion, or be so diffuse.

In comparison, molluscum is usually flesh-colored. However, molluscum may become inflamed, so the color will be more pink/red. Some people will develop a little bit of a dermatitis around molluscum, so there may also be some eczematous change around some of the lesions (Figure 3).

Figure 3. Eczematous changes around molluscum contagiosum papules.

Particularly in adults, molluscum can be a sexually transmitted disease, so you may see it more commonly on the medial thighs or in the genital areas, which can be helpful to distinguish these diagnoses.

Dr Vega: I agree, and I think that molluscum always has that typical dome-shaped appearance—a central area where there is a depression in the middle of the papule. That seems universal and often differentiates it. Do you agree? I don't usually see a lot of inflammation associated with molluscum. Usually, I just see those papules, the way they stand alone, and that very characteristic appearance that tends to give them away.

Dr Ogunleye: Yes, molluscum papules are dome-shaped with a central core, and that's definitely another one of the distinguishing features (Figure 4). Inflammation/eczema can be associated, but that is typically a secondary finding. You would also rarely see the number of lesions this patient is describing, unless that person were immunosuppressed.

Figure 4. Molluscum contagiosum. Note the dome-shaped papule with central core/umbilication.

Dr Vega: What about granuloma annulare? Isn't that something that may also present with these disseminated, papular types of lesions? Are you counting on the fact that this patient's lesions don't have that annular appearance (not circular or ring-shaped)?

Dr Ogunleye: I think the lack of annular appearance is definitely helpful. As the name implies, you will often, but not always, see more of an annular appearance in lesions of granuloma annulare (Figure 5). There are multiple subtypes of granuloma annulare, but typically, when it begins, you may note small papules, which then evolve to a more annular shape. There are rare, diffuse forms, but it would be unusual for the rash to remain only on the buttocks, elbows, and knees, as described in this patient. Joint and dorsal hand involvement can be common, though. However, the lack of orange/red/yellow appearance is a helpful distinction.

Figure 5. Annular appearance of granuloma annulare.

Dr Ogunleye: Eruptive xanthomas also tend to be a little bit more monomorphous and nodular in appearance, so you may see many papules of similar sizes. That will be seen less frequently in granuloma annulare.

Dr Vega: Can granuloma annulare erupt in a similar fashion to what this patient describes, coming on rapidly, over just a few weeks?

Dr Ogunleye: Yes; there are eruptive forms of granuloma annulare, although they occur less commonly.

Dr Vega: Where to go next? With this patient, once you have eruptive xanthoma in your differential, is it essential to recheck her lipid levels again? In this case, medical therapy for her hypertriglyceridemia may improve her skin lesions, or it may not. Otherwise, is there really anything the clinician can do about xanthelasma and eruptive xanthomas and the papules themselves?

Dr Ogunleye: First, it is important to make a distinction between xanthelasma and eruptive xanthomas. Xanthelasma is more common, and you can see that in normolipemic patients. Patients with xanthelasma have yellow, flat, thin plaques on the upper and/or lower eyelids (Figure 6). That is usually associated more with cholesterol abnormalities as opposed to triglyceride abnormalities. However, you may see xanthelasma and eruptive xanthomas appear in the same patient.

Figure 6. Xanthelasma.

Dr Vega: That makes sense.

Dr Ogunleye: Xanthelasma is a much more common condition than eruptive xanthomas. You will see xanthelasma in about 6% of the population, with or without any lipid abnormalities. However, we see eruptive xanthomas specifically in patients with triglyceride elevations or uncontrolled diabetes mellitus, so checking a lipid profile, glucose, and A1c is important. Many patients with eruptive xanthomas can have very significant hypertriglyceridemia, with results registering in the thousands. Biopsy of one of the papules should be done to confirm the diagnosis.

Eruptive xanthomas usually respond quite well to medical therapy. For example, when a patient with eruptive xanthomas is placed on a fibrate or a statin to lower their triglyceride levels, or if their diabetes is better controlled, you'll usually see those eruptive xanthomas regress. With xanthelasma, however, even if a patient does have hypercholesterolemia and their cholesterol is improved, you may not see any improvement in the lesions.

Dr Vega: This is very helpful in understanding the difference between xanthelasma and eruptive xanthomas. Thank you so much for helping me walk through that unusual case, and I look forward to speaking with you again.


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