Welcome to this October 2026 round-up of Dermatologic Surgery. We've got four pieces to get through this episode — a multicenter retrospective study on palmoplantar skin cancers, a short case series on a frozen-section mimicker you'll want filed away in memory, a propensity-matched pharmacoepidemiology study on antibiotic prophylaxis in transplant patients, and a practical comparison piece on surgical loupes. Let's get into it.

First up is a retrospective multicenter study titled "Clinical Features of Palmoplantar Nonmelanoma Skin Cancers." The clinical problem here is straightforward: nonmelanoma skin cancer is extraordinarily common, but when it shows up on the palms or soles, you're dealing with glabrous skin that behaves differently — diagnostically, it mimics benign entities, and anatomically it constrains your reconstructive options. The existing literature on this is essentially case reports, so this group set out to actually characterize a real cohort.

Methodologically, this was an IRB-approved retrospective chart review spanning three tertiary academic centers from 1990 to 2020 — a thirty-year window, which tells you immediately how rare this presentation is; you need decades and multiple referral centers just to assemble a meaningful case series. They identified cases by text-mining pathology reports for basal cell carcinoma and squamous cell carcinoma combined with location terms like palm, sole, digit, and volar, then confirmed anatomic site using clinical photographs rather than trusting the written location alone — a sensible quality-control step given how easily documentation can be ambiguous for digit versus volar surfaces. Ambiguous cases went to two board-certified dermatologists for consensus, and every basal cell carcinoma diagnosis was independently confirmed by a dermatopathologist, which matters a lot here because basal cell carcinoma on glabrous, non-pilosebaceous skin is inherently suspect and worth double-checking. There's no statistical hypothesis testing in this paper — it's purely descriptive, which is the right call for a rare-entity case series where the goal is characterization, not comparison.

The numbers: 119 tumors across 90 patients. The split was roughly 4 percent basal cell carcinoma, 59 percent invasive squamous cell carcinoma, and 37 percent squamous cell carcinoma in situ — so this is overwhelmingly a squamous-spectrum disease process. Eighty-four percent of tumors were on the palms rather than soles. Nearly half the cohort was immunosuppressed, driven mostly by solid organ transplant, and a striking one-third plus had a documented history of verruca, hinting at an HPV-driven pathway distinct from classic UV carcinogenesis. Notably, every patient was Fitzpatrick skin type one through three — the authors are appropriately cautious here, flagging this as likely referral and sampling bias rather than a true association, since HPV- and arsenic-associated palmoplantar cancers have no reason to track with pigmentation. On staging, most invasive squamous cell carcinomas were low-risk Brigham and Women's Hospital T1, with no T3 tumors at all. Mohs micrographic surgery was the leading treatment modality, used in close to half of invasive cases and in the majority of basal cell carcinomas. Recurrence occurred in about 12 percent of the squamous-spectrum tumors, with a mean time to recurrence around 20 months, and recurrence clustered in patients who'd initially been treated nonsurgically or who carried high-risk features like immunosuppression or arsenic exposure.

The authors' conclusion is appropriately measured: palmoplantar nonmelanoma skin cancer is rare precisely because this is sun-protected skin, but when it occurs, it skews toward squamous lesions with a strong immunosuppression and verruca signal, and — critically — basal cell carcinoma can still occur there, challenging the dogma that it's confined to pilosebaceous-rich skin. Limitations are the obvious ones for this design: retrospective, photo-dependent case ascertainment introduces selection bias, the skin type homogeneity likely reflects who gets referred to academic centers rather than true epidemiology, and the small basal cell carcinoma numbers limit any subtype conclusions.

For your practice, the actionable takeaway is a lower threshold for biopsying atypical palmar or plantar lesions — especially in immunosuppressed patients or anyone with a verruca history — and recognizing that glabrous-skin basal cell carcinoma, while rare, is real and shouldn't be dismissed on anatomic grounds alone. This won't change how you treat a confirmed palmoplantar keratinocyte carcinoma — Mohs for tissue conservation on functionally critical glabrous skin remains the obvious choice — but it should sharpen your index of suspicion at the biopsy-decision stage and support tighter surveillance intervals in your transplant and chronically immunosuppressed patients.

Next is a short case series, more of a practical pearl than a formal study: "Incidental Denervation-type Skeletal Muscle Change on Mohs Frozen Sections — A Potential Mimicker at the Deep Margin." This one doesn't have a methods or limitations section in the traditional sense — it's three illustrative cases meant to sharpen your frozen-section pattern recognition, so I'll walk through it as presented.

The setup: three elderly patients, ages 87 to 91, underwent Mohs for keratinocyte carcinomas of the neck — two cutaneous squamous cell carcinomas and one basal cell carcinoma — with defects extending down to platysma, trapezius, or adjacent skeletal muscle. None had any neuromuscular symptoms on review of systems. On the deep-margin frozen sections, all three showed a strikingly similar pattern: focal, sharply demarcated disruption of normal myofiber architecture, angulated and markedly atrophic fibers of varying size, stromal separation, and basophilic nuclear aggregates including pyknotic nuclear clumps — in one case with frank grouped atrophy. Critically, in every case this was separate from the tumor, with no inflammatory infiltrate and no necrotizing myopathy, and it was correctly called incidental and benign without triggering additional workup. No patient had postoperative functional deficits.

The teaching point is squarely about pattern recognition at the deep margin. These denervation-type changes — angulated atrophic fibers, grouped atrophy, pyknotic nuclear clumping — are a recognized consequence of age-related motor unit remodeling, essentially sarcopenia at the neuromuscular-junction level, and they can look histologically alarming on hematoxylin and eosin, with basophilic nuclear clumps that could plausibly be mistaken for infiltrating tumor cells in a single-cell pattern, particularly under frozen-section artifact that exaggerates vacuolization and fragmentation. The authors lay out a practical decision framework: ask whether the finding is contiguous with the tumor, whether there's destructive inflammation or necrosis suggesting something more sinister like inflammatory myopathy or a treatment-related change from prior radiation or surgery, and factor in clinical context. If genuine concern remains, send the tissue to dermatopathology for formal work-up rather than guessing on the Mohs stage.

There's no results-versus-limitations arc here to walk through — this is a "know it when you see it" alert. The practical takeaway is simple and genuinely useful: in your elderly head-and-neck Mohs cases where you're clearing down to muscle, expect that denervation-type atrophic change is a plausible incidental finding, not a sign of an invasive process, as long as it's non-contiguous with your tumor and lacks inflammatory or necrotic features. This is a "know the mimicker" takeaway rather than anything practice-changing in terms of technique — but it could absolutely save you from an unnecessary re-excision or an anxious call to pathology mid-case.

Now to the study with real statistical teeth: "Prophylactic Antibiotic Therapy Does Not Reduce Risk of Postoperative Infectious Complications in Solid Organ Transplant Recipients Undergoing Mohs Micrographic Surgery," a propensity-score matched analysis of over five thousand patients. This is a retrospective cohort study using a large claims-based database, TriNetX.

The background here is important: a prior retrospective study had suggested solid organ transplant recipients face elevated postoperative infection risk after Mohs surgery, which naturally raised the question of whether prophylactic antibiotics should be routinely considered in this population. But raising a risk doesn't tell you whether an intervention fixes it, and that's the gap this paper addresses.

Methodologically, the authors queried a federated multi-institutional database, identified transplant recipients who underwent Mohs confirmed to postdate their transplant, and split them into those who received prophylactic antibiotics around the time of surgery versus those who didn't. Now, here's the key design choice worth teaching: you cannot randomize antibiotic receipt in a retrospective database, so instead the authors used propensity-score matching. Here's what that's actually doing — logistic regression is used to estimate, for every patient, a predicted probability of receiving prophylactic antibiotics based on a whole list of measured covariates: age, sex, diabetes, hypertension, obesity, nicotine use, repair type, defect size, number of Mohs stages, anatomic site, arthroplasty and valve replacement history, and transplanted organ. That single predicted probability is the propensity score, and it compresses all those confounders into one number. Patients who received antibiotics are then matched to patients who didn't, based on having a similar propensity score — here using nearest-neighbor matching with a caliper of 0.10 standard deviations, meaning a match is only accepted if the two scores are close enough to be considered comparable. The logic is that if you can find an antibiotic-treated patient and an untreated patient who looked equally likely to receive antibiotics going into surgery, any difference in their outcomes is more plausibly attributable to the antibiotic itself rather than to the fact that, say, sicker or higher-risk patients were preferentially prescribed antibiotics in the first place. This is a smarter alternative to simply adjusting for covariates in a regression model, because it actually balances the two groups on observed characteristics before you even look at outcomes, mimicking — imperfectly — what randomization would have done in a trial.

The results: before matching, there were over six thousand unexposed patients and about twenty-six hundred who received antibiotics; after matching, they ended up with twenty-six hundred well-balanced patients in each arm. For cellulitis or acute lymphangitis within 30 days, rates were well under 1 percent in both groups — 0.7 percent without antibiotics versus 0.6 percent with — a difference that was not statistically significant and, more importantly, trivial in absolute terms. For skin and subcutaneous tissue infections more broadly, the no-antibiotic group actually had a numerically lower rate — about 1.3 percent versus 1.7 percent in the antibiotic group — again not statistically significant. So there's no signal in either direction suggesting antibiotics help, and if anything the point estimates trend the wrong way.

The authors' interpretation is clear-eyed: overall infection risk in this population is low, under 5 percent across the board, and prophylactic antibiotics did not meaningfully reduce it. This aligns with the newest antibiotic prophylaxis advisory statement, which does not universally recommend prophylaxis in transplant recipients, and it builds on a prior propensity-matched registry analysis from the American College of Mohs Surgeons that found the same null result in a mixed immunocompetent and immunosuppressed population. Limitations are the expected ones for claims-based research: you can't verify antibiotic indication, dosing, duration, or actual adherence, and coding-based outcome ascertainment always carries some misclassification risk. The authors appropriately note that a randomized trial would be the definitive next step, but call their own signal here "not robust" for routine prophylaxis.

Practically, this is close to practice-changing, or at minimum practice-reinforcing: it adds a second large, methodologically sound dataset supporting a move away from routine antibiotic prophylaxis in solid organ transplant recipients undergoing Mohs surgery, converging with current advisory guidance. The message for your clinic is that transplant status alone, in the absence of other specific high-risk features for infection, is not sufficient justification for a prophylactic antibiotic, since baseline infection risk is low and antibiotics haven't been shown to lower it further — while reserving individualized clinical judgment for patients with additional risk factors not captured in this database.

Last is a non-original piece — a practical comparison and technique guide titled "Staying in the Loop: A Comparison of Galilean and Prismatic Loupes in Dermatologic Surgery." This isn't a study with its own data; it's a synthesis of the existing ergonomics literature aimed at helping you choose and customize your magnification setup, so I'll walk through the content as the authors present it rather than forcing a results-and-limitations frame that isn't there.

The premise is sobering if you haven't thought about it recently: musculoskeletal disorder prevalence among dermatologic surgeons and trainees exceeds 90 percent, with the neck specifically affected in well over half. Loupes are positioned as a mitigation strategy, and the article focuses on the two eyeglass-mounted designs — Galilean loupes, with a straight-barrel design and shallower viewing angle requiring more neck flexion, and prismatic loupes, which use internal prisms to allow a steeper viewing angle with a more neutral neck posture.

The trade-offs are nicely laid out. Galilean loupes are lighter, offer a wider field of view — useful when you need to appreciate multiple cosmetic subunits at once — and are more versatile across patient positioning, including patients who can't be reclined due to comorbidities like heart failure, chronic obstructive pulmonary disease, or prior cervical spine surgery. But that lighter weight comes with a cost: the shallower angle demands more sustained neck flexion, and the recommended target of zero to twenty-five degrees of neck flexion to minimize musculoskeletal risk is harder to achieve with Galilean loupes. Prismatic loupes flip this: they're heavier and narrower in field of view, cost more, and work best when the patient can be reclined or semi-reclined, but they meaningfully reduce both upper trapezius and cervical erector spinae muscle activity by keeping the neck in a more neutral position — though they do increase sternocleidomastoid activity relative to Galilean loupes. So neither design is a universal winner; it's a trade between postural benefit and positional flexibility.

The article also walks through customization principles that are worth internalizing regardless of which design you choose: proper interpupillary distance and nasal bridge fit, setting working distance so your elbows rest near your torso at roughly ninety degrees, and using a magnification range of about two-and-a-half to three-and-a-half times for most procedures, dialing down when you need to appreciate broader facial subunits. They also flag loupe-mounted headlights as helpful for shadowed or contoured anatomy, but caution that added headlight weight can exacerbate forward-leaning posture, so the loupe frame itself should prioritize neutral spine alignment first.

Since this is a comparative review rather than a data-generating study, there's no statistical lesson to extract and no limitations section to report — the authors' own closing point is simply that periodic refitting matters as your physical needs change over a career, and that more research is needed on long-term ergonomic outcomes with these devices. The practical takeaway for you is equipment-level, not clinical-management-level: if your practice involves a lot of upright or non-reclinable patients, Galilean loupes may serve you better; if your setup allows consistent reclining, prismatic loupes likely offer superior postural protection over a career of cases. This is useful and actionable for your own ergonomic health, but it's not practice-changing in the sense of altering patient care — it's an occupational health recommendation worth taking seriously given the prevalence data cited.

That wraps this October 2026 review. To recap the through-line: palmoplantar keratinocyte carcinoma deserves a lower biopsy threshold in immunosuppressed and verruca-history patients; denervation-type muscle atrophy is a benign deep-margin mimicker worth recognizing in your elderly head-and-neck cases; the propensity-matched antibiotic data add further weight against routine prophylaxis in transplant recipients undergoing Mohs; and loupe selection is a meaningful but individualized ergonomic decision rather than a one-size-fits-all answer. Thanks for listening, and I'll see you next month.