Do acral biopsies in dermatomyositis patients have less-prominent histopathologic findings than biopsies from other anatomic locations?
Clinical Applications
By Kathryn Schwarzenberger, MD, FAAD, August 1, 2025
In this month’s Clinical Applications column, Physician Editor Kathryn Schwarzenberger, MD, FAAD, talks with Anthony Patrick Fernandez, MD, PhD, FAAD, about his recent Journal of Cutaneous Pathology article, ‘Histopathologic Features of Acral Skin Biopsies in Dermatomyositis Patients and Comparison to Histopathologic Features in Non-Acral Biopsies.’
DermWorld: Your recent paper compared the histopathologic features of acral skin biopsies in dermatomyositis patients with the histopathologic features in non-acral biopsies. Why did you and your colleagues study this topic?
DermWorld: For those who haven’t read your study, how did you go about conducting your assessment?
Dr. Fernandez: We reviewed all biopsies available for patients with dermatomyositis who had been seen in our department. Then we chose a single histopathologic section for each biopsy; a section with the tissue completely intact and without processing defects; and comprehensively assessed them for histopathologic findings relevant to dermatomyositis. Then, we compared the histopathologic findings in acral biopsies to the findings in biopsies from other anatomic locations. We also determined how often “hallmark” histopathologic features of dermatomyositis (vacuolar interface dermatitis, dyskeratotic keratinocytes, and presence of increased reticular dermal mucin) were present in acral biopsies. Finally, we assessed whether there were differences in the histopathologic findings in acral biopsies depending upon clinical features of dermatomyositis (acral location, dermatomyositis subtype, therapeutic regimen, or myositis-associated/myositis-specific antibody status).
DermWorld: What were your findings?
Dr. Fernandez: We found that interface dermatitis, dyskeratotic keratinocytes, and superficial perivascular inflammation were common in dermatomyositis acral biopsies. So, there were features of dermatomyositis present that could help make an accurate diagnosis. However, the majority of acral biopsies (56%) lacked one or more hallmark histopathologic feature (vacuolar interface dermatitis, dyskeratotic keratinocytes, and/or increased reticular dermal mucin). The hallmark histopathologic feature most commonly lacking in acral compared with non-acral biopsies was increased reticular dermal mucin. Overall, we found the presence of all three hallmark histopathologic features was significantly higher in non-acral compared with acral dermatomyositis biopsies (68% vs. 44%; p = 0.0021). Histopathologic features in acral biopsies did not significantly differ based on acral location, dermatomyositis subtype, therapeutic regimen, or myositis-associated/myositis-specific antibody status.
DermWorld: How do the differences in histopathologic features between acral and non-acral biopsies affect the approach to diagnosing and managing dermatomyositis in clinical practice?
Dr. Fernandez: I think the differences are specifically relevant to diagnosis and really shouldn’t affect an approach to management. An accurate diagnosis of dermatomyositis, like most inflammatory skin conditions, requires clinicopathologic correlation. So, I think the take-home message in this study is to recognize that if you see a patient who clinically fits with dermatomyositis and you perform an acral biopsy, it does not have to demonstrate all three hallmark features of dermatomyositis for good clinicopathologic correlation and to make a confident diagnosis of dermatomyositis. Additionally, I think it is important for dermatopathologists to recognize the potential differences in histopathologic findings of acral biopsies compared to non-acral biopsies, so they are not too quick to issue interpretations concluding the overall histopathologic features are not consistent with dermatomyositis.
DermWorld: Given the findings that acral biopsies often lack hallmark features, do you recommend additional diagnostic tools or criteria to improve diagnostic accuracy?
Dr. Fernandez: That is a great question. I think whether additional diagnostic tools are needed really depends on the strength of the clinicopathologic correlation. If your patient very strongly fits clinically with dermatomyositis (for example, has a heliotrope rash, Gottron’s papules and sign, shawl sign, active myositis, etc.), then our results suggest the lack of some hallmark features in acral biopsies shouldn’t necessitate a need for additional diagnostic tests to make a confident diagnosis. However, if the clinical picture is not very strong and/or is confusing, then lacking some hallmark features in acral biopsies may necessitate additional tests to give you sufficient confidence to make a diagnosis of dermatomyositis. In my opinion, assessing for anti-nuclear antibody positivity and performing a comprehensive myositis autoantibody panel would be useful ancillary tests to order in these situations. I order these tests in all patients who have clinical features suspicious for dermatomyositis. However, if you are clinician who does not routinely order these, it would be helpful to order them in patients with relatively subtle clinical features of dermatomyositis and acral biopsies lacking some hallmark histopathologic features.
Anthony P. Fernandez, MD, PhD, FAAD, is the director of medical dermatology, W.D. Steck chair of clinical dermatology, and co-medical director of CME at the departments of dermatology and pathology at the Cleveland Clinic in Ohio.
His article appeared in the Journal of Cutaneous Pathology.
Dr. Fernandez receives funding for research from Pfizer, Priovant, AstraZeneca, Castle Biosciences, and Incyte. He receives honoraria for consulting and/or speaking from AbbVie, Mallinckrodt, Biogen, Galderma, ICON research, and BMS.
Disclaimer: The views and opinions expressed in this article do not necessarily reflect those of DermWorld.
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