History of Melanoma; melanoma vs. erogenous pigmentation
Issues in Dermatopathology
Quite a bit! And I am definitely guilty of this bias!
There seem to be two kinds of dermatologists; ones that submit a comprehensive history and give a relevant differential diagnosis and ones that give absolutely no history or provide the always scintillating "rule out lesion". In the latter cases, I am sorely tempted to diagnose, "Lesion Confirmed!" One dermatologist refused to submit any clinical history. When I queried him he bluntly stated, "Of course I don't give you any history, I don't want to bias you!"
I find it interesting that at times, the comprehensive history can sometimes be a detriment to arriving at the correct diagnosis. Pathologists differ in their approach to a slide interpretation. Some, like myself, prefer to look at the slide first, formulate a diagnosis or differential diagnosis, then review the clinical history to either narrow the differential or confirm the diagnosis. Other pathologists like to review all of the clinical information before reviewing the slide. I do not believe there is a right or wrong approach, each has merit. But reviewing all of the clinical information can potentially blind one to other diagnostic possibilities. This becomes problematic when a pathologist is dealing with an unfamiliar organ system.
It is not infrequent that a biopsy requisition sheet comes in with a single diagnosis such as "rule out PLEVA" or "rule out lichen planus". As I review consults, about a third of the time, the submitting pathologist will sometimes just agree with the submitted clinical diagnosis and ask me if I agree. Since the vast majority of dermatologists are astute diagnosticians, this practice usually leads to a correct diagnosis. Yet I wonder what would happen if the biopsy actually showed classic features for one disease but the submitted clinical diagnosis was for another disease. I recently reviewed a case submitted for "rule out dermatitis herpetiformis". The submitting pathologist felt the biopsy was highly suggestive of this latter diagnosis and asked me whether I agreed. Indeed, the biopsy did show subepidermal collections of neutrophils, a classic pattern for dermatitis herpetiformis. But in addition, there were neutrophils in the stratum corneum as well. On higher magnification, there were scattered structures suggestive of fungal hyphae, later confirmed with a PAS stain. The case turned out to be a dermatophytosis! As most of us know, dermatophyte infections can mimic nearly every inflammatory dermatoses, and this case was a perfect example of this.
I have been on the receiving end of this embarrassment as well. I once reviewed a biopsy that showed a psoriasiform dermatitis. The clinical history was submitted as rule out psoriasis. I knew the submitting dermatologist to be an excellent diagnostician so I agreed with the diagnosis, signing it out as psoriasis. About two weeks later, the dermatologist called me and asked me to review the slides. The patient was now erythrodermic! He wondered whether this patient could have pityriasis rubra pilaris? With trepidation, I reviewed the slide and there, nestled within the psoriasifrom changes, was a follicular plug. Upon more careful review, there were the characteristic changes of alternating ortho- and para-keratosis. I was chagrined but called the dermatologist and told him that the original biopsy was probably most consistent with pityriasis rubra pilaris.
I would not be surprised if this bias extends to other organ systems besides skin. Furthermore, I would be interested to know if other specialties such as radiology suffer from a similar bias. Perhaps one day we may read of a study that could focus on presenting a pathologist with unknown slides and a requisition sheet containing one submitted diagnosis. Some of the slides could match the submitted diagnosis while others could be diagnostic for another disease. The same study could give the same slides to another pathologist with no history. Pathologists could be stratified depending upon experience and expertise. It would be interesting to see how any submitted history or lack of history influences the final diagnosis.
Submitted by Paul K. Shitabata, M.D.
First Posted on December 16, 2005
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