Thread by @DrStevenTChen

I've always thought #dermatology's great because of the ability to understand what might be happening underneath the skin. Let's chat today about all things #paraneoplastic! Time to get our #tweetorial/#medthread on!

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#MedEd #FOAMed #dermtwitter #medtwitter #derm pc:@dermnetnz

Caveats:
- I can't cover ALL the paraneoplastic syndrome of the skin, so apologies if I miss your favorite!
- Management of these syndromes is variable, so I'm presenting what I've learned.
- Lots of one-off case reports. I'll focus on the more common paraneoplastic stuff.

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Let's start with one we tend to think of first - #dermatomyositis (DM)! This could be it's own tweetorial, so I'll be brief here. DM is a clinical diagnosis, no biopsies are necessary! If the skin exam is classic, that's all we need.
✅heliotrope
✅shawl sign
✅gottron papule
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Some of the lesser known DM findings:
photo 1 - ragged cuticles and nailfold capillary loop changes
photo 2/3 - gottron sign (not papule) - with just erythema on MCPs and elbow
photo 4 - holster sign (rash on sides of thighs)

You don't need myositis! It can be skin limited!
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Large popluation studies have demonstrated an increase risk of associated malignancy in DM of 5-7 fold higher than the general population. A large study from Taiwan showed ~9-10 percent of DM patients had an associated cancer.

What is the most commonly associated malignancy?
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Several studies have suggested that ovarian cancer is the most likely associated malignancy. As such, women are usually are sent for transvaginal ultrasounds, and CT-scans of the torso are sometimes ordered (doctor dependent). I'll leave the rest of DM for another tweetorial!
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Take a look at this abrupt onset of scaly and itchy plaques of the hands and feet! They can quickly move on to involve the nails. This is called Bazex Syndrome, aka acrokeratosis paraneoplastica. It's associated with SCC of the upper GI or respiratory tracts!

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And what if your patient gets a new blistering eruption? Pic 1 is what it can look like, with flaccid bullae and painful erosions. Pic 2 is the more classic finding in Paraneoplastic pemphigus (PNP)! These hemorrhagic lips should really make you think of this, or SJS/TEN!

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PNP is a "messy" autoimmune blistering disease. What I mean by that is that the targeted antigen is not always the same, so the clinical presentation can be quite varied. Unlike DM above, PNP is most common associated with liquid tumors, like Non-hodgkin's lymphoma.
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Did you know that acanthosis nigricans can also be associated with malignancy? Usually we consider GI cancers as being the most likely culprit. This photo is of "tripe palm," which almost always trigger looking for cancer in the gut!
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Sweets, and other neutrophilic dermatoses (where PMNs flood the skin and cause these juicy red-purple plaques, pustules & nodules) sometimes can be paraneoplastic, especially if there's no other obvious cause! The back of the hands in particular has been assoc with leukemias.
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Finally, one brief interlude on Sign of Leser-Trelat. The eruption of many seborrheic keratoses is often quoted, but most #dermatologists I speak with don't really believe in it. That said, we all have our own anecdotal stories, so I suspect if we saw it, we'd still worry!
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As you can see, a lot of possible links between underlying cancer and skin. Another great reminder of the importance of calling your friendly #derm to help!

Leave a comment, suggestion or RT! Hope it was helpful!
Thanks for @tony_breu for the inspiration for today's topic!
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