Thread by @DrStevenTChen

PYODERMA GANGRENOSUM – a #tweetorial/#medthread

After my recent #thread on Sweet Syndrome, I thought we’d continue our discussion of neutrophilic dermatoses with a focus on PG this time! Join me below!👇👇👇

#dermtwitter #medtwitter #dermatology #dermatologia pc: @dermnetnz
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#Pyodermagagrenosum is a rare ulcerating skin condition that most of us think of in conjunction with IBD. PG can be associated with other things too, so if there’s no IBD, we should also consider other triggers, like the possibility of paraneoplastic processes.
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PG is a neutrophilic dermatosis, so like Sweet Syndrome, it starts as a pustule, & ulcerates from there. Remember pathergy is a classic associated finding with neutrophilic derms. See my #tweetorial on sweet syndrome for a discussion of pathergy!

https://twitter.com/DrStevenTChen/status/1165710613399527424?s=20

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However, the end result of PG usually has a characteristic look on physical exam.
-Rolled borders (overhanging edge over the ulcer)
-Violaceous / “gun-metal grey” borders (this tells us it's still "active" and prone to keep going
-Cribiform (net like) scarring (pic2)
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The issue with PG is that on pathology, they are full of PMNs, so it’s hard to rule out an infection. Remember that if a bx is necessary, we need to:
a) consider taking a tissue cx to rule out infx
b) remember pathergy occurs, so it could worsen
c) bx at the ulcer edge!
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IMPORTANT POINT FOR PROCEDURALISTS: Don’t forget about PG when you have a post-operative wound that keeps “getting infected.” These pts get debrided, path keeps coming back looking like infx, but nothing grows. It could be PG, and each debridement just adds fuel to the fire!
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Before we get to treatment, let’s talk about some terms that might get a little confusing.

Pyoderma Gangrenosum =/= Pyoderma

Pyoderma is just a generic term for pustular stuff in the skin.

Also, Pyoderma Gangrenosum =/= Ecthyma Gangrenosum.

What is ecthyma gangrenosum?
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Ecthyma gangrenosum describes the skin changes seen with a (usually) gram negative rod bacteremia, most commonly pseudomonas. Exam shows necrotic & sometimes retiform lesions. If this rash is noted, blood cultures and broad spectrum antibiotics should be started ASAP!
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Moving on to PG tx. Acutely, systemic steroids are often used since quick treatment can help prevent ulceration. In chronic cases, we can target PMNs with dapsone or colchicine, a couple of our favorite anti-PMN drugs. Topical versions are also helpful (steroids & dapsone).
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When these tx options don’t work, we reach for heavier duty immunosupressants. A subspecialist should probably be involved for mgmt. In addition, chronic wounds benefit from a wound specialist. Because of pathergy, we avoid mechanical debridement & use enzymatic instead.
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A ? that comes up is what to do when pts with a h/o PG need surgery. Well, @AMostaghimi @KristinaLiuMD & co answered this with the following paper. My take away is that it's a low but real risk. Lower risk procedures perhaps just need close monitoring
jaad.org/article/S0190-…
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& remember how we need to look for associated diseases. Knowing what to look for is overwhelming. Luckily, @AMostaghimi, @MishaRosenbach, @DanielButlerMD & others published a @jamaderm paper that found depending on pt characteristics, risks differed.
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ncbi.nlm.nih.gov/pmc/articles/P…

Recap:
-PG is a neutrophilic dermatosis with characteristic exam findings.
-New cases of PG should be investigated for underlying causes/triggers.
-Treatment is immunosuppression or anti-neutrophilic.
-Patient with h/o PG have a low but real risk of flare at surgery.
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That was a really quick whirlwind tour of PG, which can be confusing & difficult to tx. As a parting gift, here’s a youtube clip from “Mystery Diagnosis” where my former professor (now #derm chair @TuftsMedicalCtr) was highlighted for her help!
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