Can nail clippings save lives?

By Kathryn Schwarzenberger, MD, FAAD, April 1, 2023

In this month’s Clinical Applications column, Physician Editor Kathryn Schwarzenberger, MD, FAAD, talks with Adam Rubin, MD, FAAD, about his Journal of Cutaneous Pathology paper, ‘A call for nail clipping histopathology to become an essential component of the routine evaluation of melanonychia: Benefitting patients as a triage and surgical planning maneuver.’

DermWorld: You and your co-authors recently published a manuscript advocating for the use of nail clipping histopathology in the routine evaluation of melanonychia. I suspect many of us are now comfortable sending nail clippings for fungal studies, but I imagine that sending them for melanocytic lesions is less common. Can you tell us more about this?

DermWorld: How are nail clippings best obtained and sent for these studies?

Dr. Rubin: The best way to submit nail clippings for melanonychia is to clip evenly perpendicular to the direction of nail growth and be sure to include the area of pigmentation within the nail clipping. An even nail clipping will help the histopathology technicians orient and process the nail clipping best. Ideally, the nail clipping would include nail plate from the entire clippable length of the nail.

DermWorld: Is this a technique that all dermatopathologists will be comfortable doing? Does this require special training?

Dr. Rubin: Dermatopathologists (and dermatopathology laboratories) are already used to handling nail clippings for onychomycosis, and the basic procedures for evaluating the nail clippings are very similar. No special training or special laboratory reagents are needed aside from what is already available. As the presence of melanocytes or melanocyte remnants has now been established as a reproducible warning sign associated with nail unit melanoma when visualized in the nail plate, dermatopathologists not already familiar with this work will be educated about the importance of this sign through publications such as DermWorld. Other histopathologic features found in the evaluation of melanonychia from nail clippings — such as localizing the pigmentation to different parts of the nail clipping, and therefore the origin of a lesion in the nail matrix — are easily learned through publications on this topic and lectures by nail experts.

DermWorld: Can you confidently diagnose melanocytic lesions using nail clippings? I’m assuming a nail matrix biopsy will still be necessary to confirm the diagnosis.

Dr. Rubin: The presence of melanocytes or melanocyte remnants in a nail clipping is a warning sign for the potential of a nail unit melanoma. However, in order to establish the diagnosis of nail unit melanoma, sampling from the nail matrix is required. An analogous situation can be considered when a dermatologist takes a sample of an area of periungual pigmentation (Hutchinson sign). In that case, there may be atypical findings in the periungual skin which by themselves are not diagnostic of a nail unit melanoma, but suggest that it is present, and similarly, sampling from the nail matrix is needed. Sampling of the nail matrix is the gold standard for diagnosis of nail unit melanocytic lesions. A nail clipping with melanocyte remnants or histopathologic features of the Hutchinson sign associated with a nail unit melanoma can be considered to be peripheral zones of that lesion.

DermWorld: I will admit to being a bit of a dinosaur, but we never did this “in my day.” When did this innovative — and obviously relatively simple — technique arise?

Dr. Rubin: We have known for some time that nail clippings can have versatility in diagnostic applications aside from onychomycosis. However, the urgency and call for use of this technique happened very recently. We reported for the first time in 2015 that a nail clipping was used to make the diagnosis of a nail unit melanoma. This was an amelanotic melanoma (J Cutan Pathol. 2015 Aug;42(8):505-9).

Then, three years later, we published another incidence of nail unit melanoma ultimately being diagnosed after a nail clipping, this time from a pigmented nail that also had onychomycosis (J Cutan Pathol. 2018 Nov;45(11):803-806). As a dermatopathologist that focuses on nails, I had noticed that melanocytes were common in the nail plates of specimens of melanoma, and in particular nail avulsions as part of nail melanoma specimens.

Then colleagues from Korea published a manuscript in 2022 that demonstrated the relationship between the number and distribution of melanocyte remnants in nail plate areas associated with other nail unit tissue and nail unit melanoma (J Cutan Pathol. 2022 Apr;49(4):331-337). My colleagues Sook Jung Yun and Eckart Haneke wrote a commentary on this manuscript, noting among other things the link between this work and the potential applications to nail clippings and their potential findings in nail unit melanoma.

I recently had another patient who had concerning melanonychia on her thumb who refused a nail matrix biopsy, but did allow me to do a nail clipping, which showed the same findings that had already been described, and she was diagnosed with nail unit melanoma after a nail matrix biopsy. She is reported in this current manuscript (J Cutan Pathol. 2022 Dec 14. doi: 10.1111/cup.14377. Epub ahead of print). With this accumulated evidence, and the other potential diagnostic benefits of nail clippings for melanonychia, I thought this simple technique of a nail clipping — which can be done easily as part of a dermatologist’s workflow and is familiar to patients as part of routine grooming and can be easily evaluated by dermatopathologists — would be a helpful innovation to the routine evaluation of melanonychia and benefit patients worldwide. Nail clippings can save lives!

DermWorld: I have to ask, because I know we will be asked: Do you have any issues getting insurance to reimburse for this novel technique?

Dr. Rubin: Nail clippings taken for melanonychia are processed and billed in a similar manner to all other dermatopathology specimens and do not require any special approval. Personally, I have never had any billing issues for nail clippings I have sent in the evaluation of melanonychia, or nail clippings for any other indication, including the evaluation of onychomycosis. The application of nail clippings for the routine evaluation of melanonychia is novel, but the processes have been in place all along. Advancements in nail histopathology have shown us the value of this application, and the many benefits and diagnostic applications and information which can be obtained in this clinical setting.

Adam I. Rubin, MD, FAAD, is associate professor of dermatology in the department of dermatology at the Hospital of the University of Pennsylvania in Philadelphia. His paper was published in the Journal of Cutaneous Pathology.

Disclaimer: The views and opinions expressed in this article do not necessarily reflect those of DermWorld.

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