Cold Iron Truth

Melanoma in situ: It’s hard to know what you don’t know

Why it matters that patients screened by a PA were significantly less likely to be diagnosed with melanoma in situ.


The emergency department locum tenens staff recruiter was persuasive. “It’s a quiet little ER where you can study and sleep.” I was board certified in internal medicine and had trained in a busy urban emergency department. This was just the spot to make a little folding money and study for my mock dermatology boards, I thought.

And so, on a Saturday night in rural Texas, after grinding rust out of a pipe fitter’s eye and stitching up two brawlers from the local biker bar, I was faced with treating a comatose kid brought in after a car crash. He had not been wearing a seat belt, and his car had rolled over on his head.

I was way over my skill level, but I was lucky. I was able to stabilize him and, after several long hours, I got him on an emergency helicopter into Dallas.

But the experience changed me. I realized I did not know enough to deal with this case on my own. After making it through that night in the ED, I never put myself in that position again.

I now knew what I did not know.

Skin biopsies: Do physician assistants save money?
A study recently published in JAMA Dermatology reminded me of that experience in Texas. The study compared the accuracy of skin cancer diagnoses by physician assistants (PAs) and dermatologists for about 20,000 patients and 33,000 patient encounters for skin cancer screening between January 2011 and December 2015 at dermatology offices affiliated with the University of Pittsburgh. No significant differences in diagnoses of nonmelanoma skin cancer and invasive melanoma were found.

The finding that jumped out to me, though, was that patients screened by a PA were significantly less likely to be diagnosed with melanoma in situ, the stage when melanoma is 100% curable. Yet, those patients screened by PAs underwent a lot more skin biopsies – 36% more skin biopsies per melanoma in situ diagnosed, compared with patients of dermatologists. Interestingly, in the health care system studied, any PA with a question about a patient can ask an attending dermatologist to see the patient. Did that factor account for the diagnostic comparability for nonmelanoma skin cancer and invasive melanoma? Did the PAs not ask for help on the missed melanomas in situ? If so, I believe this may be a situation of PAs not knowing what they didn’t know.


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