Pattern matching is an important skill for all
physicians. It is rarely discussed these
days despite all the continuous hype about artificial intelligence replacing
doctors by reading x-rays and other lab tests.
I taught a course in diagnostic reasoning for about 12 years and the
examples of pattern matching I used were from dermatology and
ophthalmology. The dermatology
experiment was a straightforward comparison of dermatologists to primary care
physicians looking at the same slide set of rashes and skin lesions (1). The dermatologists were correct more often,
faster at diagnosing, and able to correctly diagnosis equivocal cases compared
with the primary care physicians.
I want to be clear that does not mean that primary care
doctors don’t do a good job. Some are so
good that dermatologists know that they need to attend to the diagnosis and
treatment of some physicians who refer them significant numbers of patients
with melanoma and other types of cancer.
All these factors were probably in my subconscious when I decide to call
to see a dermatologist.
It was not easy. The
first appointment was a teleconference and I would call it a swing and a miss. I
was given a very expensive prescription for ocular rosacea that did nothing.
When I called again to be seen in person, I was given an elaborate algorithm based on how many problems I wanted to be seen about. The more problems – the
longer the wait. I decided to go outside
of my usual healthcare providers to a private clinic closer to my home.
I have noticed a gradual accumulation of dermatology
problems with age. I have made every effort to avoid direct sunlight. If I must be outside at any time when my
shadow is shorter than my height, I am wearing a high SPF shirt and sunscreen,
a baseball cap, and wrap around polarized sunglasses. I have probably been
sunburned twice in my life and tanned once. About 2 years ago I noticed a
ring-shaped red lesion on my right forearm.
Every now and then it seemed to burn but generally it was static. I saw my primary care MD and he did a
scraping and potassium hydroxide preparation to see if it was ringworm (tinea
corporis). It was not, so he told me to apply the betamethasone ointment
that I typically use for eczema to the area.
I did for a couple of weeks and there was no effect.
At about the same time, I happened to notice a blue spot on
the lateral aspect of my left ankle.
That is a difficult area to see.
I went into see a primary care MD who used an ophthalmoscope for
magnification and concluded it was a collection of pigmented cells that did not
look like a melanoma. She said she would
describe it in my chart including recording the diameter so it could be followed
along by primary care.
I described all these problems to the Dermatologist's assistant
before he walked in the room. I had
photos of all the dermatology products I had been using and what had been tried
in the past. Even though the pattern
matching diagnosis in Dermatology is good, like other areas of medicine – the treatments
seem to be hit or miss and even then the response seems to vary over time. I made a note to myself that I should look
for papers claiming that these are placebo treatments or it is just all
regression to the mean. But I doubt that
there are any anti-Dermatologists out there complaining about that and too many diagnoses and too many medications.
The intake form that I completed was just 2 pages long and
there was an occupation section probably to consider environmental
exposures. When the Dermatologist came
in he was very cordial and talkative. He
established that we both went to the same medical school (27 years apart),
lived in the same neighborhood while we attended, and knew some of the same
professors. He took the history and
clarified the technical points to his assistant who had now become his
scribe. He used a dermatoscope to inspect
the lesions and make rapid diagnoses on the right forearm (actinic keratosis), left ankle (fibroma secondary to trauma) and left
malar area (actinic keratosis). He recommended freezing the
malar area and forearm with liquid nitrogen and said the fibroma was just a
skin reaction to some trauma that did not require treatment. At that point we
went into a more detailed discussion of the rosacea and ocular rosacea and
failed treatments with doxycycline and tacrolimus. He recommended a compounded product of azelaic
acid, metronidazole, and ivermectin, advised me of the cost, and has his assistant
set that up. It was a very efficient process – the diagnoses, freezing
treatments, and discussion took about 20 minutes. At the end all of the follow up,
prescriptions, and documentation was done and he was moving on to the next
person.
There are times when it pays to see an expert and this is
an illustration of one of those times. I
had been looking at these lesions for 2 years and trying to take the next
steps. There are as many barriers to
seeing a Dermatologist as there are to seeing a psychiatrist. I knew enough to monitor these lesions and
they did not seem to get worse, but they were also not improving. After 2
years I got the definitive diagnoses and treatment I had been looking for as
well as reassurance that the ankle lesion was not a melanoma.
This is an impressive result compared with most physician
visits. Even considering that there were
a couple of things that did not fit. Sun
exposure for one. I am what is referred
to as a white fish in upper Midwest vernacular. That means apart from my blue veins and the
redness of rosacea – my skin is generally as white as the background of this page. I had some early exposure to people with skin
cancer and have been very diligent about keeping my skin and retinal exposure to
direct sunlight at a minimum. I suppose
there are other factors at play such as age and know there are senile
keratoses – but this did not resemble typical lesions in my dermatology texts
or online. The Dermatologist predicted that the freezing treatment would cause
these lesions to slough off and be replaced by normal smooth skin. I have a follow up in 3 months to see if that
happens and if the compounded topical rosacea medication works.
I am currently studying high prevalence polygenic diseases
and have included eczema on that list.
Some estimates say that 20% of the population may have it. There is the association with asthma but in
my case as my asthma improved with age, I developed eczema and then worsening eczema.
I
expect there will be many parallels with psychiatric disorders and diseases
when my comparison is done.
In the meantime, a Dermatologist in the right setting is a good consultant to
have in your corner.
George Dawson, MD, DFAPA
References:
1: Norman, G.R.,
Brooks, L.R., Rosenthal, D., Allen, S.W., & Muzzin, L.J. (1989). The
development of expertise in dermatology. Archives of Dermatology, 125,
1063–1068
This is the original reference I used in my course on the diagnostic process and how not to make a mistakes. The first author has written significant papers about this.
Graphic:
I mapped the dermatology conditions onto the body outline. If someone has a better body outline or one that they use on a standardized form and you want to send it my way - please do. I can make a much better graphic if the outline is a separate shape. The actinic keratoses areas on the map are probably both only 2 cm in diameter. The rosacea can happen anywhere on the face and most annoyingly on the eyelids. The eczema is a whole body condition that started out subtly as intense pruritis on the extremities and eventually spread to the abdominal area, chest, and back. Pruritis is the most significant symptom with occasional lesions that looks like abrasions. It can be exacerbated by skin contact with allergens like ECG electrodes.
