Thread by @DrStevenTChen

It's been ages since I've put out a #dermtwitter #tweetorial, so I thought what better way than to share a diagnosis that was the original motivator for me to become a dermatologist! A 🧵 on:

PEMPHIGUS VEGETANS!

#MedEd #dermatology #medtwitter #FOAMEd @healourskin #pemphigus
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What is Pemphigus Vegetans? This is where breaking down the terms can be super helpful. It's the diagnosis we give when pemphigus has the morphology of vegetative plaques.

A #tweetorial on pemphigus if you need it👇

https://twitter.com/DrStevenTChen/status/1484569902744748032?s=20&t=rwSrCR-84l-No_-EwOFCVA

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Some people think Vegetans occurs when Vulgaris goes untreated. Others think it's just a rare subtype of vulgaris.

Given the clinical findings, the path looks different with pseudoepitheliomatous hyperplasia (but still with a suprabasal split!).

pc:dermatologyadvisor.com/home/decision-…
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This photo from @VisualDx is great at illustrating the overlap. You can see the collarettes of scale around the edge, demonstrating a prior bullous process. Yet, centrally, the vegetative plaque is the most prominent!

🌟Remember - collarettes are footprints of old blisters!
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That said, there are 2 different subtypes with some proposed differences:

Neumann type: from longstanding vulgaris, morphology turns vegetative over time. More widespread and recalcitrant to treatment.
Hallopeau type: Presents initially with pustules instead. More limited.
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However, speaking from personal experience - I have seen cases of Vegetans that didn't fit either type (different type of antibody)!

The point is that this is a rare entity that clearly has its roots in pemphigus. The details after that are still being investigated!
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And anywhere you can get pemphigus vulgaris, you can also get Vegetans! So while it's classically in the intertriginous areas, it doesn't have to be. Check out this example of pemphigus vegetans of the scalp!
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So what's on your differential diagnosis?

This one is more for my #dermtwitter peeps since it's a little niche, but if you have a "classic" vegetative plaque in the intertriginous areas, what would you consider?
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I'd personally think about:

Hailey-Hailey
Vegetans
Acanthosis Nigricans
An atypical intertrigo
Contact dermatitis

There are other intertriginous eruptions like SDRIFE and hidradenitis, but the morphology is different enough to differentiate.

Here are pics of Hailey Hailey!
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So what's the treatment? The same as Pemphigus Vulgaris. This is an antibody mediated disease, so we target the creation of those antibodies. That means medications like: Rituximab, Mycophenolate, and IVIG, to name a few.
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But all these medications suppress the immune system, so I don't use them lightly. I have a long discussion with my patients about their risk of infection (among other adverse effects) so that they know what to look out for afterward.
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SUMMARY:
✅ P Vegetans is a rare form of pemphigus, possibly from undertreatment over time.
✅ Pathology is different, with psedoepitheliomatous hyperplasia.
✅ Usaully intertriginous, doesn't have to be.
✅ Treatment is directed at auto-antibodies.

Thanks for joining!
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