Our Surprising Hide

Sometimes in Emergency Medicine you want vignettes you can toss about at dinner parties. Other times you want facts with which you can impress your residents. And once in while you want to pull an unexpected diagnosis out of a hat for the sake of your patients: rare, esoteric, and, every so often, correct. Today’s column gives us all three.

Skin. Emergency Dermatology. Sure, you’ve all been trained in the House of Goddish 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 go and see 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 which are guaranteed to engender respect and awe when you produce them like a magician’s trick.

1. Phyto-photo dermatitis. Think making margaritas in the sunshine. After a (usually unnoticed) exposure to certain plants (be it lime, lemons, celery, figs, or any fruity accessories with their furanocoumarins), in the sunshine (UVA – so peak summer, or mojito season) within 24 hours a bullous, linear rash comes up, which fades within a few days into hyperpigmentation. The innocuous history and sun-exposed area distribution is the key to diagnosis. Treat with, you guessed it, steroids (in the early phase only).
2. 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.
3. Id eczema. Also known as autoeczematisation. I rather like this one, with its hat-tip to Freudian theory. Id, as you well know, is the part of the personality which works on the pleasure principle, and the gratifications of desire. How this relates to widespread systemic eczema I don’t have the foggiest, but still, one can ponder. This id reaction is peculiar – it is an acute generalised dermatitis distant from the original and localised dermatitic condition. It is the skin going out 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 it steroids.
4. Leucocytoclastic 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 is variable, the treatment is 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.
5. Levamisole vasculitis. Levamisole is a now defunct antihelminth, which is still used on the streets for its dubious by-product of potentiating the effect of cocaine. This female predominant vasculitis progresses from erythema to purpura to necrosis then eschar, on ears, noses and malar eminences, via an aggressive immunological response. It is not pretty. Steroids may be beneficial. Cocaine cessation, unsurprisingly, is recommended.
6. 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, treated with hard core emollients. You can pronounce it rhyming with Eczema Dracula, but only if you’re being ridiculous, like me.
7. 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 marvellous things about the richness of dermatology (Dermnet NZ https://www.dermnetnz.org, the premier global skin site, has upwards of 2300 entries), is how often even the most learned of skin specialists will admit to not knowing precisely why the dermis pathologises 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.