Welcome back to the journal review. This month we're covering the May twenty twenty-six issue of Dermatologic Surgery, and we've got four pieces worth your time — a retrospective cohort study on infection risk after ear wedge excisions, a short comparative piece on ultraviolet lamps for finding biopsy sites, a case report on repurposing frozen section pathology for a dermatologic emergency, and a case report on an unusually fast-growing squamous cell carcinoma in a brand-new tattoo. Let's get into it.

First up is a retrospective cohort study titled "Assessing the Risk: Infection After Mohs Surgery and Ear Wedge Excision Repair," out of the University of Rochester. The clinical problem here is one you've probably internalized without ever really interrogating it: the 2008 advisory statement on prophylactic antibiotics in dermatologic surgery tells us to reach for antibiotics before ear wedge excisions, and that recommendation traces back to a citation of an eight-and-a-half percent infection rate. But if you look at where that number actually comes from, it's a single-center descriptive study of only thirty-five cases, and critically, it never even tested whether giving prophylactic antibiotics changed the infection rate. So practice has been anchored to a fairly thin evidentiary reed for almost two decades, even as more recent work has suggested infection rates under five percent at high-risk sites including the ear. This study set out to re-characterize that real-world infection rate in a modern cohort.

Methodologically, this is an IRB-approved retrospective cohort pulling every ear wedge excision performed by two Mohs surgeons at Rochester from January twenty seventeen through December twenty twenty-four. They collected the usual risk-factor scaffolding — age, sex, body mass index, smoking, diabetes, immunosuppression, anticoagulation — plus tumor type, number of Mohs stages, tumor size, final defect size, whether prophylactic antibiotics were given, and surgical site infection within thirty days, with infection defined either as clinical suspicion plus a positive culture, or clinical suspicion alone. The authors don't spell out explicitly why they chose a retrospective design, but it's the obvious methodological choice here — surgical site infection after a specific anatomic subtype of Mohs closure is a fairly uncommon event, so you need years of accumulated cases at a single institution just to generate enough infection events to analyze at all, and a prospective trial powered for that would be logistically brutal. For statistics, they ran univariate logistic regression to get odds ratios for each variable, then used the Mann-Whitney U test to compare continuous variables between the infected and non-infected groups.

The results: one hundred fourteen cases, mostly basal cell carcinoma and squamous cell carcinoma, overwhelmingly male patients, and a low burden of active smoking, but close to a third with diabetes and about one in eleven immunosuppressed. There were only three postoperative infections in the entire cohort — two culture-proven, growing Streptococcus pneumoniae and a Pseudomonas–Enterobacter combination, and one diagnosed clinically. That's an overall infection rate of two-point-six percent, which is dramatically lower than the eight-and-a-half percent figure the 2008 advisory statement leans on. Notably, only two patients in the whole cohort received prophylactic antibiotics, and neither of them got infected — so this cohort essentially demonstrates a low baseline infection rate in the near-total absence of prophylaxis. The one factor that came out as statistically significant on regression was increasing age, with each unit increase in age nudging up the odds of infection, and the mean age in the infected group was around ninety compared with around seventy-eight in the non-infected group — a gap that's both statistically significant and clinically believable given wound healing and immune senescence in your oldest patients. Nothing else — not body mass index, smoking, diabetes, tumor type, number of stages, tumor size, or defect size — reached significance.

The authors' discussion is refreshingly direct: given this low observed infection rate, they do not recommend routine prophylactic antibiotics for ear wedge excision repair during Mohs surgery, and they raise the appropriate stewardship concern — that continuing to prescribe prophylaxis based on outdated, thinly-sourced data risks adverse drug effects, contributes to antibiotic resistance, and adds unnecessary cost, all for a benefit that this data doesn't support. I'd flag a limitation the authors don't dwell on themselves: with only three total infection events, that regression model is working with a very small numerator, so the confidence interval around the age odds ratio is wide and this should be read as hypothesis-generating for that specific finding rather than definitive. It's also a two-surgeon, single-institution cohort, which limits generalizability to practices with different closure techniques or patient populations.

Practically, I'd call the headline message here genuinely practice-relevant — this adds to a growing body of evidence that routine prophylactic antibiotics for ear wedge excisions are probably unnecessary for most patients, and it gives you a contemporary, reasonably-sized denominator to cite instead of that thirty-five-patient study from nearly two decades ago. The age signal is interesting but not yet actionable in a granular way — I wouldn't say you need a hard age cutoff for selective prophylaxis based on three events, but it's reasonable to keep advanced age in mind as a soft factor in your individualized risk-benefit conversation, particularly in patients in their nineties.

Next, a shorter piece — "Comparative Analysis of Ultraviolet Lamps for Identifying Biopsy Sites in Dermatologic Surgery." This isn't a full study with a defined cohort or statistics; it's better thought of as a practical, observational tool comparison, so I'll walk through it as that. The clinical problem is one every Mohs surgeon has lived through — a patient shows up weeks or months out from an outside biopsy with no photograph, and you're left hunting for a faint, healed biopsy scar under ambient light. The traditional tool for this is the Wood's lamp, emitting broad-spectrum ultraviolet light in the 320 to 400 nanometer range, but the authors note that cheaper, commercially available ultraviolet black lights at more specific wavelengths have become widely accessible, which prompted a head-to-head comparison.

They tested three light sources — the traditional Wood's lamp, a 365 nanometer black light, and a 385 to 395 nanometer black light — examining biopsy sites in patients presenting for Mohs surgery and photographing the results for side-by-side comparison under consistent conditions. All three lights could highlight the biopsy site to some degree, but the 385 to 395 nanometer light was the standout — brighter, with sharper delineation of the biopsy margin, and notably it also performed well in a Fitzpatrick skin type four patient, which is a meaningful practical point since fluorescence-based tools don't always translate cleanly across the skin of color spectrum, and it's good to see that explicitly tested here.

The authors' bottom line is that this narrower-band 385 to 395 nanometer black light outperformed both the classic Wood's lamp and the 365 nanometer alternative for outlining biopsy site margins, and as a bonus it's smaller, cheaper, and more portable than a traditional Wood's lamp. I'd frame the takeaway honestly: this is a small, qualitative, single-center comparison without a formal sample size or statistical analysis, so it's not practice-changing evidence in the rigorous sense — but the downside risk of trying it is essentially zero. It's an inexpensive handheld device, and if it genuinely gives you crisper margin visualization for those frustrating "where's the biopsy scar" moments, particularly in patients with tricky pigmentation, it's a very reasonable one to add to your surgical tray.

Third, a case report titled "Frozen Sections in Clinic as a Real-Time Diagnostic Adjunct for Urgent Dermatologic Cases." The framing here is that frozen section processing is obviously our bread and butter in Mohs surgery, but the authors point out it's almost never deployed outside that context in general dermatology, even in acute situations where a rapid answer could meaningfully change management. They illustrate this with a striking case.

A forty-one-year-old man with a complicated transplant history — pancreas transplant, a failed renal transplant, on dialysis, and immunosuppressed on tacrolimus and mycophenolate mofetil — came in for a hospital follow-up visit after being discharged for headaches and blurry vision that had been attributed to occipital neuralgia. During that admission he'd also been noted to have umbilicated papules on his face and hands, which were called molluscum contagiosum. Cryptococcus was on the differential at the time, an HIV test came back negative, and cryptococcal antigen serology was drawn on discharge day — but the sample was rejected by the lab for hemolysis, so that data point was simply lost, and he was sent home with expedited outpatient follow-up instead of an answer. In clinic, his headache, fatigue, and blurry vision were still present, which kept cryptococcal meningitis high on the differential. The dermatologist took a shave biopsy of a periocular umbilicated nodule and split the specimen — half went for standard formalin-fixed permanent processing, and half was frozen-sectioned with toluidine blue right there in the Mohs lab while the patient waited. The frozen section showed florid encapsulated yeast forms consistent with Cryptococcus neoformans, and the patient was sent directly to the hospital, where cerebrospinal fluid, serology, and tissue culture all confirmed cryptococcal meningitis.

There's no methods or limitations section here in the traditional sense — it's a single illustrative case — but the teaching point is sharp and worth carrying into your own practice. Any dermatologist with in-house Mohs frozen section capability is sitting on a diagnostic tool that can be repurposed well beyond skin cancer margin assessment. Dermatology residency training in dermatopathology is generally sufficient to recognize a handful of urgent, pattern-recognition diagnoses — encapsulated yeast forms being a clean example — even without a dermatopathologist immediately available. And critically, frozen sections don't have to replace permanent processing; they can simply buy you same-day decision-making, letting you triage a patient straight to the hospital instead of waiting days for serology or paraffin-embedded sections to come back. This is squarely a "keep in your back pocket" pearl rather than something that changes routine practice, but for the occasional immunosuppressed patient with a concerning umbilicated eruption and systemic symptoms, it's the kind of tool that can genuinely change same-day outcomes.

Last, a case report: "Squamous Cell Carcinoma Arising in a New Tattoo." A seventy-year-old woman with a history of multiple basal cell carcinomas above the waist presented with a three-week history of a five-millimeter papule with surrounding erythema on her left ankle, sitting right inside a tattoo she'd received just one week before the lesion appeared. She'd already been treated empirically with a week of cephalexin for presumed cellulitis without any improvement before making it to dermatology. Biopsy showed a well-differentiated squamous cell carcinoma with black tattoo pigment present in the specimen, and special stains and cultures for fungal, bacterial, and atypical mycobacterial organisms were all negative, with no palpable regional nodes. She underwent Mohs, cleared in two stages, ended up with a one square centimeter defect, and was closed primarily. At four-month follow-up she'd healed well with no sign of recurrence.

The discussion here situates this within the small but growing literature on tattoo-associated malignancy — melanoma, squamous cell carcinoma, basal cell carcinoma, dermatofibrosarcoma protuberans, and lymphoma have all been reported arising within tattoos, with red and black pigments most frequently implicated. No causal mechanism has been definitively proven, but the proposed pathways are worth knowing: mechanical trauma from the injection process itself triggering inflammation and potential mutagenesis, a persistent foreign-body inflammatory response to the retained pigment, pigment-altered ultraviolet absorption generating damaging breakdown products, and outright carcinogenic contaminants in some inks, including polycyclic aromatic hydrocarbons, heavy metals, and primary aromatic amines. Interestingly, across the reviewed literature, red ink is the more common trigger for squamous cell carcinoma specifically, cited in roughly half of reported cases, while black ink accounts for only about one in five — even though black is actually the more frequent culprit behind melanoma and basal cell carcinoma in other reports. What makes this particular case worth publishing is the timeline: well-differentiated squamous cell carcinoma in tattoos typically takes anywhere from a month to years to develop, and even the faster keratoacanthoma-type variant usually has a median onset around a month. A visible tumor at one week is genuinely unusual, and it's exactly the kind of timeline that pushes clinicians toward an infectious diagnosis first, which is what happened here with the empiric cephalexin course. The authors note the expected infectious timelines for context — bacterial infections like Staphylococcus aureus or Streptococcus pyogenes typically present within about two weeks, atypical mycobacteria over one to three months, and HPV-driven lesions sometimes not for years to decades — which makes the negative infectious workup here all the more important in cementing the malignant diagnosis. The patient chose Mohs specifically for margin control balanced against preserving as much of her tattoo as possible, which is a reasonable and increasingly common patient preference we should expect to see more of as tattoo prevalence rises.

There's no formal limitations section since this is a single case, but the teaching point is straightforward and clinically actionable: don't let a very short latency period falsely reassure you away from biopsying a new, non-healing, antibiotic-refractory papule within a recent tattoo. The conventional teaching that tattoo-associated squamous cell carcinoma takes at least a month to appear shouldn't stop you from biopsying an odd lesion at one week if it's not behaving like cellulitis.

That wraps up this month's issue — a solid argument against reflexive antibiotic prophylaxis for ear wedge excisions, a cheap gadget worth trying for biopsy site identification, a reminder that your frozen section capability has value well beyond the Mohs suite, and a case that should lower your threshold for biopsying atypical lesions in new tattoos regardless of how soon they appear. Thanks for listening, and we'll see you next month.