Welcome to this December twenty twenty-five review from the Journal of the American Academy of Dermatology. Four pieces caught my eye this month — a simulation study out of Italy rethinking how we triage melanoma excisions, a transplant dermatology case series on sirolimus and nonmelanoma skin cancer, a digital epidemiology study tracking public interest in tanning beds, and a sharp letter to the editor on a pitfall in dysplastic nevus margin reporting that's directly relevant to how we counsel patients. Let's get into it.

First up is a brief report out of the Province of Trento, Italy — a prospective cohort study paired with a simulation model, looking at how to prioritize melanoma excisions in secondary care. The background here is worth sitting with: essentially all of the diagnostic-delay literature in melanoma focuses on primary care delays — time to presentation, time to referral — and almost nobody has looked rigorously at the bottleneck that happens once a patient is already in a dermatology surgical queue. In Trento, dermatologists have been using a simple binary urgency code — urgent versus non-urgent — to decide who gets excised first. The question this group asked is whether that judgment-based system actually works, and whether folding in additional patient variables could do better.

Methodologically, they prospectively collected three hundred and one excised lesions over six months, capturing the assigned urgency code alongside age, sex, nevus count, and prior melanoma history. They ran a logistic regression to see which of these variables actually predicted a histologically confirmed melanoma. Then — and this is the more novel piece — they built a Monte Carlo simulation testing twenty-four different prioritization strategies across a range of surgical slot availabilities, from thirty-five slots up to one hundred fifty, running each scenario ten thousand times to get stable estimates. The logic for choosing simulation over, say, a prospective trial of alternate triage systems is fairly obvious once you think about it: you cannot ethically or practically randomize real patients to a worse triage algorithm to see how many melanomas you miss. Simulating detection rates against a known, already-collected cohort lets you stress-test competing prioritization rules against the real distribution of disease without touching patient care. That's my read on the rationale — the authors don't spell it out explicitly, but it's the standard justification for this kind of in-silico approach.

The results were fairly clean. Both age and the dermatologist's urgency code were independent predictors of melanoma on regression — each additional year of age bumped the odds up modestly, but urgent-code status increased the odds more than fivefold, which tells you the existing gestalt-based triage isn't worthless, it's just incomplete. The simulation confirmed this: at a baseline of seventy-seven available slots, a combined age-and-urgency weighted strategy detected about thirty-five melanomas, compared to twenty-four with urgency-only prioritization, and only nine with no prioritization at all. Even when they choked the system down to just thirty-five slots — a genuinely resource-constrained scenario — the composite strategy still caught twenty melanomas versus only four with no prioritization. And the advantage held up as they scaled capacity all the way to one hundred fifty slots, so this isn't just a small-numbers artifact.

The authors are appropriately modest in the discussion. This is single-center, Trento-specific, over just six months, so there's no way to speak to long-term outcomes like mortality or recurrence — the simulation predicts detection efficiency, not survival benefit, though obviously earlier detection is the whole game in melanoma prognosis. They're upfront that real-world barriers exist too: clinicians may resist deprioritizing a lesion they've already decided to cut, there are medicolegal optics to formalizing an age-based deprioritization scheme, and you'd need staff retraining to implement it. Practically, I'd call this interesting and directionally practice-informing rather than immediately practice-changing for most of us doing our own scheduling — but if you're in a system with real excision queues and waitlists, especially in the UK-style or European public health model, this is a genuinely actionable framework: age-weighting your triage on top of clinical gestalt costs you nothing and the simulated yield increase is substantial.

Next, a case series with a strong translational message — sirolimus and its protective effect against nonmelanoma skin cancer in kidney transplant recipients, out of University of Wisconsin. You all know the background cold: solid organ transplant recipients carry something like a sixty-five to two-hundred-fifty-fold increased risk of nonmelanoma skin cancer, calcineurin inhibitors like tacrolimus compound that risk by further crippling tumor immunosurveillance, and the TUMORAPA trial already showed that switching to sirolimus, a mammalian target of rapamycin inhibitor with intrinsic antitumor activity, cuts squamous cell carcinoma rates with benefit sustained out to five years. What this paper adds is a much longer look-back — a retrospective case series of two hundred fourteen adult kidney transplant recipients on sirolimus between two thousand three and two thousand twenty-three — essentially asking whether that protective signal holds up over decades rather than years.

The design choice here is straightforward and appropriate: this is a question about rare-ish long-term events across a large transplant registry, so retrospective cohort analysis is really the only feasible design — you're not randomizing transplant patients to carcinogenic immunosuppression to prove a point. They classified biopsy-confirmed squamous cell and basal cell cancers, attributed cancers occurring more than two years after sirolimus initiation to sirolimus and earlier ones to tacrolimus, and modeled incidence with negative binomial regression adjusted for age and sex — negative binomial being the right tool here because tumor counts are overdispersed count data, not a simple yes/no outcome.

The magnitude of effect is the headline. Age- and sex-adjusted tumor incidence was roughly zero-point-four tumors per twelve treatment-months on sirolimus, versus around four-point-three on tacrolimus — that computes to something over a ninety percent reduction in overall tumor burden, and the effect was consistent whether you looked at squamous cell or basal cell histology specifically, with squamous cell showing the more pronounced drop. Male sex carried more than double the tumor risk relative to female, and there was a nonlinear age effect with tumor rates peaking around age fifty-eight at transplant. Follow-up in this cohort stretched out remarkably far — up to twenty-six years for some patients — which is really the value-add over TUMORAPA's five-year data.

Limitations are the expected ones for a retrospective single-institution series: no randomization, so residual confounding around who gets switched to sirolimus versus who stays on tacrolimus is a real concern, and the authors flag that future work needs to look at combination regimens, since calcineurin inhibitors and mTOR inhibitors are increasingly used together for synergistic immunosuppressive and antitumor effect rather than as an either-or choice. For practical purposes, I'd call this practice-affirming rather than practice-changing — it doesn't overturn anything, but it substantially strengthens the case for proactively raising a sirolimus conversion with the transplant team in any patient you're seeing with recurrent or high-volume squamous cell carcinoma, particularly if they're male and in that fifth-to-seventh decade risk window.

Third, a digital epidemiology study — a nice change of pace methodologically — looking at Google search behavior for tanning beds before and after the World Health Organization's twenty-oh-nine reclassification of ultraviolet radiation from tanning devices as a Group One human carcinogen. Background: that reclassification was backed by a meta-analysis showing roughly a seventy-five percent increase in melanoma risk with tanning bed use before age thirty-five, and we know indoor tanning has broadly declined nationally since, though frequent use persists in certain subgroups. This study asks a more granular question — did public interest actually shift measurably around that reclassification, and does it vary meaningfully by state.

Methodologically they used Google Trends relative search volume for the term "tanning beds," chosen because it consistently had the highest relative search volume among related terms, pulling monthly data from two thousand four through late twenty twenty-four and comparing pre- and post-reclassification averages with linear regression and Welch's t-tests, then correcting for testing across all fifty states using the Benjamini-Hochberg false discovery rate procedure. This is a reasonable design for what it is — a low-cost, retrospective look at population-level interest trends — but it's worth being explicit with yourself that relative search volume is a proxy for curiosity, not a proxy for actual tanning bed use.

Nationally, search interest declined significantly after the reclassification, though there wasn't a sharp inflection point right in twenty-oh-nine — the decline looks more gradual or delayed than a clean before-and-after step change. After correcting for multiple comparisons, eighteen states showed statistically significant shifts. Florida, Illinois, California, and Texas showed the largest declines, while Utah and Idaho actually showed significant increases in search interest. The authors' interpretation is that state-level regulation — many of these states passed minor-access bans or parental consent requirements, several of them enacted after the WHO announcement — likely did more heavy lifting in shaping behavior than the international classification itself, while states like Utah and Idaho that still permit use with parental or physician consent didn't see the same drop.

The honest limitations here are important: Google Trends measures interest, not behavior, so a decline in searches doesn't confirm a decline in actual tanning bed use, and the changes could just as easily reflect advertising shifts, media coverage, or unrelated public health campaigns rather than the WHO action specifically. There's also a seasonal signal — search peaks in spring and early summer — which the authors suggest is actionable for timing public health messaging. Overall, I'd file this as interesting but not clinically actionable in the sense of changing anything you do at the bedside — it's more useful as ammunition for supporting state-level tanning regulation advocacy and for timing patient-education campaigns seasonally, rather than something that changes surgical or diagnostic practice.

Last is a letter to the editor, a direct response to a previously published decision aid for patients with dysplastic nevi being considered for re-excision, and this one is squarely relevant to daily practice. The letter authors — from Mayo Clinic and University of Connecticut — praise the original patient decision aid but push back on one specific line in it: the statement that a "negative margin means no cells are left at the edge of the biopsy." Their point is that this is only true for the edges of the sections that actually get examined pathologically — it doesn't account for the well-documented possibility of a false-negative margin on a punch or shave specimen.

The teaching point, illustrated with a simple grossing diagram in the letter, is one every one of us already knows intuitively but rarely says out loud to patients: whether a biopsy margin reads as positive or negative depends heavily on how the specimen happens to be bisected during grossing, which dictates where the thin representative histologic sections are actually cut from. An oblong lesion bisected across its short axis, for instance, can easily miss nevus cells extending along the long axis, producing a falsely reassuring negative margin. Even a technically well-executed punch or shave, done with full intent to remove the lesion, may still miss the common subclinical "trailing" margin of a dysplastic nevus that extends beyond the visible clinical border. This isn't new data — they cite the existing literature on inadequate sampling in punch-excised melanocytic lesions and the known negative predictive value problem with dysplastic nevus margins — but the value of the letter is reframing this as a patient-communication issue, not just a pathology-methods footnote.

Their proposed fix is simple and directly usable in your own consent conversations: a positive, especially inked, margin generally does mean incomplete removal, but a negative margin on a punch or shave specimen does not reliably mean the nevus is gone. That asymmetry is exactly why re-excision can be reasonable even in the face of a "clear" margin, particularly for severely atypical or dysplastic lesions, and it's a genuinely practice-relevant point — not because it changes what you do surgically, but because it gives you sharper, more honest language for explaining to patients why you're recommending re-excision despite a pathology report that reads as reassuring.

That wraps our four pieces this month — a simulation model that makes a real case for age-weighted melanoma triage in constrained systems, long-term real-world confirmation that sirolimus meaningfully protects transplant patients against nonmelanoma skin cancer, a population-level look at how regulation rather than global classification seems to be driving tanning bed interest, and a sharp reminder from the letters section about the limits of a "negative" biopsy margin in dysplastic nevi. Thanks for listening, and I'll see you next month.