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What Lies Beneath

In Praise of Skin

Johnston, Michelle MBBS

doi: 10.1097/01.EEM.0000586460.98697.f6
What Lies Beneath

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Sometimes in emergency medicine you want vignettes you can toss about at dinner parties. Other times you want facts to impress your residents. Today's column gives us all three.

Skin. Emergency dermatology. Sure, you've all been trained in the House of God-like ways of dermatology. If it's wet, dry it. If it's dry, do the opposite. When you don't know, give steroids. When you do know, give steroids. But, oh, how this underestimates the magnificent complexity of our integument.

Let us take a moment to admire our skin. So complex. No biological engineering feat has come close to replicating its function. Self-healing, protective, temperature-regulating, stretchy, sensual, biologically active, and very good at keeping all the organs and other stuff inside; you've got to admit it's pretty awesome. But mysterious, so mysterious. How often are you asked to see a patient with a rash, and you end up coming out of the cubicle mumbling that it is either an exanthem or it's immunological? Yes, some sort of immunology, right there.

Let us then run through a few diagnoses guaranteed to engender respect and awe when you produce them like a magician's trick.

  • Phytophotodermatitis. Think making margaritas in the sunshine. After an exposure (usually unnoticed) to certain plants (be it lime, lemons, celery, figs, or any fruity accessories with their furanocoumarins) in the sunshine (UVA rays, so peak summer or mojito season), a bullous, linear rash comes up within 24 hours. It fades within a few days into hyperpigmentation. The innocuous history and sun-exposed area distribution are the key to diagnosis. Treat with—you guessed it—steroids (in the early phase only).
  • Tinea incognita. Steroids gone wrong. This occurs when the original pathology is a fungal (dermatophytic) infestation, which is inappropriately treated with steroid creams. This dampens down the inflammatory response, and simply drives the rash underground, like a Cold War spy. It is dully itchy and does not have the flare-like appearance of usual tinea. It needs all steroid (and calcineurin inhibitor) topical treatments ceased and skin scrapings performed. Once the diagnosis is confirmed, it is all standard antifungals and time.
  • Id eczema. Also known as autoeczematization. I rather like this one, with its hat-tip to Freudian theory. Id, as you well know, is the part of the personality that works on the pleasure principle and gratifications of desire. How this relates to widespread systemic eczema I don't have the foggiest, but one can ponder. This id reaction is peculiar; it is an acute generalized dermatitis distant from the original and localized dermatitic condition. It is the skin reacting in sympathy. Its pathophysiology is widely debated, somehow immunologic- or cytokine-mediated, but the treatment is, yes, again, you are correct, keep it wet, and give steroids.
  • Leukocytoclastic vasculitis. I admit, I'm just fond of the name of this one, and like to seek it out so that I can pronounce the diagnosis as though I am queen. The rash is palpable purpura of the lower limbs, and is kind of the Henoch-Schönlein equivalent of older folks. It's a small vessel, skin-predominant vasculitis. The causes are legion; it may be idiopathic or triggered via a number of immunologic pathways. The course and treatment are variable, and usually the patients are well under the care of long-term specialists (rheumatologists and immunologists) by the time you can actually congratulate yourself on the correct diagnosis.
  • Levamisole vasculitis. Levamisole is a now-defunct antihelminth, but it is still used on the street for its dubious byproduct of potentiating the effect of cocaine. This vasculitis predominantly affects women, and it progresses from erythema to purpura to necrosis, and then eschar on the ears, noses, and malar eminences via an aggressive immunological response. It is not pretty. Steroids may be beneficial. Cocaine cessation, unsurprisingly, is recommended.
  • How about some rapid-fire diagnoses? Eczema Craquelé, the cracked appearance of overly dry skin, also known as asteatotic eczema, occurs in low humidity on limbs, and is treated with hard-core emollients. You can pronounce it by rhyming with eczema Dracula, but only if you're being ridiculous like me.
  • Other fabulous names: Cheiropompholyx (vesicular contact dermatitis of the palms of the hands), DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms), and Grover's disease (intensely itchy red spots round the torso of middle-aged white men).

One of the most marvelous things about the richness of dermatology (Dermnet NZ, the premiere global skin site, has upwards of 2300 entries; https://www.dermnetnz.org) is how often even the most learned of skin specialists will admit to not knowing precisely why the dermis pathologizes the way it does. Complexity and mystery have the same address in many of the conditions. Wonderful organ. Extraordinary diagnoses. And mostly down to steroids or not. How fabulous is that?

Dr. Johnstonis a board-certified emergency physician, thus the same as you but with a weird accent. She works in a trauma center situated down the unfashionable end of Perth, Western Australia. She is the author of the novel Dustfall, available on her website, http://michellejohnston.com.au/. She also contributes regularly to the blog, Life in the Fast Lane,https://lifeinthefastlane.com. Follow her on Twitter @Eleytherius, and read her past columns at http://bit.ly/EMN-WhatLiesBeneath.

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