Thread by @DrStevenTChen

In honor of my recent trip to Taiwan, where I was eaten alive by mosquitoes, I thought I'd put together a #tweetorial/#medthread on...

BUGBITES and STINGS!

#dermtwitter #dermatology #dermatologia #medtwitter #MedEd #FOAMEd pc:@dermnetnz
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First of all, did you know that #dermatologists refer to bug bites and stings as an "arthropod assault?" In case you ever wanted to throw that into your next conversation....
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While there are some rashes that can be classic for certain types of bites/stings, many are rather nondescript. So when you see a #dermatologist with what looks like bug bites, we are often making an educated guess. Classically, you see pink edematous papules/plaques.
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As you all know, there isn't much to do for these types of more banal lesions except to treat the itch with a topical steroid. Quick plug for my steroid tweetorial from a month ago if you want more information on how to prescribe them!

https://twitter.com/DrStevenTChen/status/1123605778127052800

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But let's talk about the more specific patterns with certain critter's "assault" on the skin. Before that, don't forget that epidemiologic patterns for the geographic territory you're in make a difference (eg: lyme or chagas). That said, #climatechange is messing with it all!
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A bite from a tick can bring with it a variety of tickborne illnesses. Lyme disease gives the classic erythema migrans rash (photo 1). We all know to treat with doxycycline, but remember that if the tick isn't attached for >24-36 hours, really shouldn't need abx.
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As a #derm, one of my favorite findings is this (which the pt'll call a new mole):

Same rules apply as above for antibiosis, but if you're in an endemic area, and unclear how long the tick's been attached, you can give a 1x prophylactic dose of doxy. Oh, and remove the tick!
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While we're on the topic of tick borne illnesses, remember that Rocky Mountain Spotted Fever can be deadly, and also comes with a rash. BUT - the rash is later in the symptoms that develop, so if you suspect RMSF, don't wait for the rash, just start the doxycycline!
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The other common referral ? is bedbugs. This one is tough, because the spots look just like the nondescript bugbite photo. What helps is the configuration (breakfast, lunch, and dinner). Basically, the pink papules are in a line or clustered.

pc: from nhs.uk/conditions/bed…
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Bed bug bites are treated symptomatically, but an exterminator is usually advised. Patients can also try to get rid of them themselves with a bunch of different kits and products available online. Bedbugs themselves and the bedbug poop can be found in seams of the mattress.
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A brief mention about spider bites - Patients LOVE to blame spider bites for everything. It's usually rather unlikely, but if you're in the right geographic region, you could consider one like a brown recluse bite, but that usually causes quite a severe necrotic reaction.
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And while they aren't technically bites or stings, infestations are often a cause of itch and rash. Scabies (pic1), for example, is more of an issue with mites living on the skin than a true "assault." Other bugs can also cause itch, like lice (aka pediculosis - pic2).
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Flea bites tend to come up around the ankles, by virtue of where you find the fleas. So finding this exam and nothing else might lead to asking about risk factors for fleas (eg: pets).
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One other general point - patients who have a very exuberant reaction to any arthropod assault can be reacting because of an underlying medical problem. If you see a bullous arthropod process, what lab should you send?
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Usually, patients with a bullous/exuberant reaction to an arthropod assault would potentially warrant a CBC. This is because these reactions have been reported in CLL!!
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To recap:
- bugbites can be nondescript on skin exam.
- treatment is usually supportive with topical steroids.
- certain patterns can help with dx and may require different tx.
- Don't forget epidemiologic data when deciding on probability of certain disease processes!
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I'm going to stop there, because there are obviously a ton more possible bugs and reactions to cover. I'll let #dermtwitter and #medtwitter fill in more as they see fit! Hope this was helpful!
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