Dr. Nathaniel J. Jellinek discusses raising awareness about nail issues as well as specific Mohs techniques to improve nail unit squamous cell carcinoma (SCC) treatment outcomes.
Nathaniel J. Jellinek, MD, FAAD, is Assistant Clinical Professor, Department of Dermatology Warren Alpert Medical School, Brown University, Providence, Rhode Island, and President, Council for Nail Disorders
“[We know] that squamous cell carcinoma in the nail unit is fraught with delays in diagnosis. That is because it can mimic several other diagnoses, including common diagnoses such as chronic paronychia. Because of that and… a general unease with biopsying, nail unit tumors tend to have delays in diagnosis, and that’s something we see also in the literature,” said Nathaniel J. Jellinek, MD, FAAD, who presented “State of the Art Approach to the Diagnosis and Treatment of Nail Unit Squamous Cell Carcinoma” at the 2022 American Academy of Dermatology (AAD) Annual Meeting.
“Knowing that, we’re trying to raise people’s awareness about nail issues that are either verrucous and/or wart-like, people with high risk factors such as high-risk HPV, tobacco, immunosuppression, [or a] history of ionizing radiation (such as a radiologist), and then to biopsy early to make these diagnoses.”
According to Dr. Jellinek, one of the reasons many nail conditions are underdiagnosed may be because general dermatologic screening exams focus on the skin.
“…a more subtle nail sign such as a band of longitudinal erythronychia can just be overlooked because, [as] one of my pathology professors taught me, the eye cannot see what the mind does not know. So if you’re not aware that that is a thing, then you’re just going to gloss over it. But once you start getting tuned to those things, you see them everywhere… longitudinal erythronychia is one of the presentations of nail unit squamous cell carcinoma in situ. So that’s the main reason we biopsy those.”
Notably, nail unit squamous cell carcinoma is also highly associated with high-risk HPV, said Dr. Jellinek.
“So much so that recent literature suggests it can be considered a sexually transmitted infection. So that’s an interesting point and teaches us something when we’re seeing patients with this to consider asking them about exposure to high-risk HPV and considering sexual contacts and screening.”
Changing Treatment and Outcomes
Mohs surgical techniques have been the driver behind achieving better outcomes for nail unit melanomas, said Dr. Jellinek.
“In most cases, what we’re able to do is spare the digit because, historically, for nail unit squamous cell carcinoma and nail melanoma in situ even, the treatment was amputation or disarticulation at some level.”
Not only are these drastic measures no longer needed in most cases, but data from multiple centers worldwide show very good cure rates, said Dr. Jellinek.
Still, cure rates are not as good as those achieved with Mohs surgery on skin lesions, which may be due to multiple factors, he said.
“One, it’s associated with high-risk HPV. So when we treat the carcinoma, there may still be high-risk HPV around and if that’s oncogenic, it could trigger another mutation and you have a second primary in that high-risk field.”
Two, the anatomy is complex, said Dr. Jellinek.
“You have a nail plate. You have 1 mm to 3 mm of nail tissue and then the bone, so we’re really operating on this hard, rigid structure. And very frequently the carcinomas dive and either abut or superficially invade the periosteum or even the superficial portion of the bone.”
Thus, it may be more difficult for some surgeons to get the deep margin they are more comfortable achieving in skin tissue, said Dr. Jellinek.
Dr. Jellinek and his colleagues at their regional referral center have developed a few techniques to improve success, with 12-year data that show no recurrences to date, he said.
“One thing we often do is we remove the tissue down to the bone.”
In this initial step it’s common to see tumor at the deep margin, said Dr. Jellinek.
“And that could be for multiple reasons. You could have a true positive. It’s there, it’s invading bone.”
It could also be a false positive detection of basic tumors at the deep plane, he said.
“Either way, you’re in a quandary because you have tumor at the depth.”
According to Dr. Jellinek, using a bone cutter to achieve clear margins has been instrumental to cure rate successes.
“Some people can use a chisel, but a bone cutter allows you to take clean specimens of the soft tissue and bone at the depth of the defect, process them by frozen section, and achieve clear margins.”
Another way to improve cure rates: Leave the nail plate attached when taking Mohs layers, said Dr. Jellinek.
“…when you cut tissue with the nail intact to process for frozen sections, you do not avulse the nail. You cut through the nail plate, and you process the tissue with the nail plate attached.”
This practice runs counter to the standard approach surgeons are taught: to avulse the nail plate before excision, said Dr. Jellinek.
“…because the nail plate is so adherent to the nail bed epithelium, when you avulse the nail plate, you actually remove some of the nail bed epithelium with it so that when you excise the nail bed and look at the margins, you don’t have epithelium to make your call as to whether it’s clear or positive.”
According to Dr. Jellinek, this change has made once-complex cases much simpler to diagnose and treat.
“When you remove it with the plate, you actually see the nail bed epithelium perfectly. It’s easy read. All of the sudden, these cases that were challenging for me very early in my career are now quick cases… they’re relatively straightforward. The pathology is excellent and replicable. So that’s been a neat advance I’ve seen in my career.”
Finally, while graft and flap reconstructive approaches have been used historically to cover the wound, his team has found success in healing by granulation, said Dr. Jellinek.
“We let most of them heal by second intention, and they heal amazingly well…without intervention.”
In terms of the general dermatologist performing nail diagnosis and treatment, there’s definitely a role, and organizations including the AAD, ASDS, and ACMS all have nail surgery hands-on workshops, said Dr. Jellinek.
“They’re very high yield, and at the AAD, they’re directed towards the medical dermatologist.”
The first step in getting involved is questioning diagnosis and that means biopsies, said Dr. Jellinek.
“There are hopefully an increasing number of people who are comfortable doing those biopsies. Most Mohs surgeons are comfortable doing those biopsies and that would be a logical second referral. I think most hand surgeons are comfortable doing these biopsies that would also be another referral. I think on the toes, there are many podiatrists who are comfortable doing those biopsies.”
“The Council for Nail Disorders is an organization that brings together dermatologists, hand surgeons, generalists, podiatrist, all with the focus on nail diseases and so allowed me to appreciate the sort of the shared pathology that we all see in our practice.”
