People like to quote George Santayana, who said that those who forget history are doomed to repeat it. Few realize he was referring to the treatment of cutaneous fungal infections.
OK, he wasn't exactly referring to ringworm, but he could have been.
In complex matters like politics and human relations, history is hard to learn from because no two situations are exactly the same.
Scaly skin rashes, however, are not complicated at all. There are only a few possibilities, the most common of which are fungus and eczema. Two simple tests can distinguish them: a potassium hydroxide (KOH) prep and a culture. Even without testing, simple observation of clinical response should do the trick. A steroid cream makes a fungus worse and eczema better; an antifungal cream makes fungus better and does little or nothing for eczema.
Yet generations of nondermatologists continue to treat inflammatory rashes—nummular eczema, balanitis, submammary intertrigo, and so forth—with antifungal creams. My question is not how they can make that mistake; anyone can make a mistake. My question is why they keep making it. Why do so many experienced clinicians, decade after decade, never seem to get any better at making this straightforward, clear-cut distinction?
A close analysis is needed. The mechanism for perpetuating this simple mistake may shed light on the persistence of errors of greater consequence. I will map the intellectual progress of a doctor I'll call XY, to avoid gender bias. There are four steps:
1. Childhood training. Along with everyone else, XY learns early that skin diseases are connected with dirt. The germs presumed to cause rashes are dirty too, especially fungi. Tell Jane she has eczema and she protests, "But I shower every day!" Joey can't fathom why he breaks out—he washes so often. And of course everybody wears flip-flops in the locker room, since we all know what you catch there.
2. (Non)education. In medical school, XY learns nothing about managing ordinary skin problems. The occasional slide presentation may provide passing mastery of discoid lupus or acanthosis nigricans, conditions of interest to the presenter. XY departs medical school with the same assumptions about the rash-dirt nexus with which he or she entered.
3. Pavlovian reinforcement. When XY encounters skin problems during residency, the rash is always incidental to the patient's true problem: heart disease, cancer, and other illnesses of real importance. If the skin issue is noted at all, senior staff will instruct XY that it is probably fungal and treat accordingly. Should XY have the temerity to suggest otherwise and propose treatment with a topical steroid, faculty will exclaim, "Steroids weaken the immune system—you can't put them on an infection!" XY won't make that mistake again.
4. Indifference. Clinical practice will provide XY with few stimuli to unlearn default fungal assumption. When the disease at hand is actually fungal, antifungal creams make the patients better. More often, such creams are irrelevant except as emollients, but the patients don't call to complain. Perhaps the rash never bothered them that much, or the eczema remitted on its own. XY therefore never discovers the error. More severe rashes may generate a dermatologic consultation. The dermatologist's referral letter is read with little interest, if any. XY expects no collegial pats on the back for getting rashes right, fears no lawsuit or public ridicule at grand rounds for getting them wrong.
The mistake therefore does not correct itself, and life goes on.
Santayana notwithstanding, history lessons are hard to learn. When matters are complex, its lessons may be nuanced and ambiguous. What history teaches may be hard to understand or painful to accept.
Then again we may not learn because of simple indifference; we just aren't motivated to bother. Glory and shame are good motivators. Professional integrity and intellectual curiosity should work too, but the evidence suggests they often don't. XY is not interested in learning the distinction between fungus and eczema, XY's educators are not interested in teaching it, and XY's patients aren't bothered enough by the problem to bring the issue to a head.
We all make mistakes. Scaly skin rashes are just an example of the process by which we can go on making the same ones. It might be useful now and then to stop and investigate how many errors we make every day because we can't be bothered to find out that we made them.