1/
Why exactly do the lesions in pityriasis rosea appear in the “Christmas Tree” pattern?
Well, in honor of today being #Christmas, let’s do a brief #dermatology/#dermtwitter #tweetorial on…
PITYRIASIS ROSEA!
So what say you? What’s the reason for the Xmas Tree pattern?
Why exactly do the lesions in pityriasis rosea appear in the “Christmas Tree” pattern?
Well, in honor of today being #Christmas, let’s do a brief #dermatology/#dermtwitter #tweetorial on…
PITYRIASIS ROSEA!
So what say you? What’s the reason for the Xmas Tree pattern?
2/
PR presents in "Langer's Lines," aka the skin tension lines. This paper notes diseases in this pattern seem to have activated leukocytes in the pathophy, which could be explained by other papers looking at how skin stretch impacts immune response!
sciencedirect.com/science/articl…
PR presents in "Langer's Lines," aka the skin tension lines. This paper notes diseases in this pattern seem to have activated leukocytes in the pathophy, which could be explained by other papers looking at how skin stretch impacts immune response!
sciencedirect.com/science/articl…
3/
This same paper points out a limited group of skin diseases that can have this distribution:
- PR
- Secondary syphilis
- Sign of Leser Trelat
- Mycosis Fungoides
Ultimately, the cause of this distribution might have to do with skin tension, but is best described as unknown.
This same paper points out a limited group of skin diseases that can have this distribution:
- PR
- Secondary syphilis
- Sign of Leser Trelat
- Mycosis Fungoides
Ultimately, the cause of this distribution might have to do with skin tension, but is best described as unknown.
4/
Although it's helpful to know the distribution of PR (along with its differential diagnosis), it's also helpful to think of the primary lesion.
Remember that PR starts with a herald patch (pc: @dermnetnz) which comes after a URI in some patients. (Some are asymptomatic!)
Although it's helpful to know the distribution of PR (along with its differential diagnosis), it's also helpful to think of the primary lesion.
Remember that PR starts with a herald patch (pc: @dermnetnz) which comes after a URI in some patients. (Some are asymptomatic!)
5/
A few days later, a disseminated rash appears along the skin tension lines on the torso>extremities.
The herald patch & the disseminated rash can have what is described as "branny" scale (think oat bran).
See my tweetorial on scale for more details!
A few days later, a disseminated rash appears along the skin tension lines on the torso>extremities.
The herald patch & the disseminated rash can have what is described as "branny" scale (think oat bran).
See my tweetorial on scale for more details!
6/
Remember that in darker skin types, the erythema can be hard to spot! Just compare these two photos of PR! This is where knowing the primary lesion (papule/plaque) and the characteristic of the secondary change (branny scale) is critical to making the diagnosis.
Remember that in darker skin types, the erythema can be hard to spot! Just compare these two photos of PR! This is where knowing the primary lesion (papule/plaque) and the characteristic of the secondary change (branny scale) is critical to making the diagnosis.
7/
PR is a viral illness, thought to be related usually to HHV 6 or 7. As such, the disease runs its course over a few weeks (~6-8 is what I tell patients).
A recent cochrane review looked at possible treatments for PR. What do you think it found as helpful agents?
PR is a viral illness, thought to be related usually to HHV 6 or 7. As such, the disease runs its course over a few weeks (~6-8 is what I tell patients).
A recent cochrane review looked at possible treatments for PR. What do you think it found as helpful agents?
8/ The paper (cochranelibrary.com/cdsr/doi/10.10…) found the following:
- acyclovir might helps PR clear faster. It might also help with itch.
- erythromycin might similarly hasten rash resolution and itch, but even less evidence than acyclovir.
- other options aren't great.
- acyclovir might helps PR clear faster. It might also help with itch.
- erythromycin might similarly hasten rash resolution and itch, but even less evidence than acyclovir.
- other options aren't great.
9/
What do I do? I tend to reassure my patients since it's a self-limited disease. For those that are very bothered, I would consider antiviral therapy. Also good to remember that there are some drug-induced PR-like rashes, so a quick medication review is helpful.
What do I do? I tend to reassure my patients since it's a self-limited disease. For those that are very bothered, I would consider antiviral therapy. Also good to remember that there are some drug-induced PR-like rashes, so a quick medication review is helpful.
10/
RECAP:
- PR is viral (eg HHV 6/7), & resolves after a couple months.
- Acyclovir has the most evidence, but might be unnecessary if asx.
- Morphology helps (Papules/plaques with branny scale), and erythema in lighter skinned individuals.
- PR-like rash can be drug induced.
RECAP:
- PR is viral (eg HHV 6/7), & resolves after a couple months.
- Acyclovir has the most evidence, but might be unnecessary if asx.
- Morphology helps (Papules/plaques with branny scale), and erythema in lighter skinned individuals.
- PR-like rash can be drug induced.
11/11
Thus ends my brief #tweetorial/#medthread on Pityriasis Rosea! In honor of this skin eruption, a very Merry Christmas to all, and best wishes for a Happy New Year!
#MedEd #FOAMEd #dermatologia #tweetiatrician #medtwitter
Thus ends my brief #tweetorial/#medthread on Pityriasis Rosea! In honor of this skin eruption, a very Merry Christmas to all, and best wishes for a Happy New Year!
#MedEd #FOAMEd #dermatologia #tweetiatrician #medtwitter
