Welcome back to the journal review. This is the October twenty twenty-six issue of Dermatologic Surgery, and we've got four pieces worth your time this month — an original study on melanonychia and nail melanoma risk out of Singapore, a case report on Mohs for recurrent chromoblastomycosis, a surgical pitfall case involving a scalp dermoid cyst, and a reconstructive conundrum on a large perioral defect. Let's get into it.

First up is the original article: an eighteen-year review of melanonychia and nail melanoma risk in Singapore, out of the National Skin Centre.

The background here is familiar territory for anyone practicing in or near an Asian population — nail apparatus melanoma makes up a disproportionately large slice of melanoma in Asian countries, somewhere in the range of ten to twenty-five percent of all melanomas in Japan, China, and Korea, compared to under four percent in Western populations. The clinical problem is the one we all know: distinguishing early nail apparatus melanoma from benign longitudinal melanonychia is hard, diagnostic accuracy among dermatologists for early lesions has been reported as low as the mid-forties to mid-fifties percent, and delay translates into worse prognosis despite nail melanoma behaving comparably stage-for-stage to cutaneous melanoma. What hadn't been done before is a dedicated look at this question in Singapore's multiethnic population, so that's the gap this paper fills.

Methodologically, this is a retrospective observational chart review spanning eighteen years, from 2004 to 2021, pulling patients coded with melanonychia-related diagnoses and specifically cross-checking against nail melanoma codes to avoid missing cases that weren't initially flagged as melanonychia — a sensible capture strategy given how easily early nail melanoma could be coded or labeled as something else. The statistical lift here is modest and appropriate to the data: descriptive summaries throughout, and for the comparison of interest — what features associate with malignant histology — they used the Fisher exact test rather than a chi-square. Worth pausing on why: Fisher's exact test is the right tool when you have categorical, two-by-two style comparisons with small cell counts, which is exactly the situation here given only eight confirmed nail melanoma cases. Chi-square relies on a large-sample approximation that breaks down when expected cell counts are low; Fisher's exact test instead calculates the exact probability of the observed table arising under the null hypothesis, directly, without that approximation. It's the correct and conservative choice for rare-outcome data like this, and it's a good instinct any time you're mining a dataset with single-digit event counts.

The key results: out of about fifteen hundred fifty patients presenting with longitudinal melanonychia over eighteen years, a predominantly Chinese, female, under-fifty population, only around one in six were referred for biopsy, and of those, about seventy percent actually underwent the procedure. Among the roughly two hundred biopsied, eight cases of nail apparatus melanoma turned up — three in situ, five invasive — for a biopsy-cohort incidence of four percent. Every single invasive case showed the advanced triad of nail plate destruction, nail bed ulceration, and a positive Hutchinson sign, which is a clinically important point: by the time these had obvious red flags, they were already invasive. The two factors that reached statistical significance for predicting malignancy were age fifty and older and blue-collar occupation — the latter a modest, borderline association, but one the authors plausibly tie to repetitive microtrauma rather than socioeconomic status per se, consistent with existing literature linking acral melanoma to manual labor and trauma. Classic red-flag features — color variegation, irregular borders, width greater than three millimeters — were descriptively common in the melanoma group but didn't reach statistical significance here, which the authors attribute to the very small number of confirmed cases rather than suggesting those features aren't real risk markers. Postbiopsy complications were not trivial — nail dystrophy and other issues occurred in roughly one in five biopsied patients, overwhelmingly after shave biopsy, the most commonly used technique.

On discussion and limitations, the authors are refreshingly candid: their four percent incidence is lower than the five to ten percent range reported in other regional and international series, and they offer competing explanations rather than claiming a true biological difference — possibly a more conservative referral threshold in Singapore, possibly delayed care-seeking given a median time of about a year from onset to first consultation. The small number of confirmed melanoma cases is the central limitation, and it's why none of the classic clinical red flags reached significance despite being present in half the cases. This is retrospective chart review methodology, so there's inherent missing-data risk, which the authors address by excluding variables with substantial missingness.

Practically, here's what matters for your practice: this doesn't change biopsy technique or thresholds in a prescriptive way, but it reinforces two things worth carrying forward — age over fifty and blue-collar or manual-labor occupation should raise your index of suspicion even in the absence of textbook dermoscopic red flags, and the fact that every invasive case in this cohort already showed nail plate destruction and ulceration is a sobering reminder that waiting for those features means you've likely already missed the in-situ window. This is useful epidemiologic context and risk-stratification nuance rather than a practice-changing mandate — it doesn't tell you to biopsy earlier or differently, but it should nudge your threshold down in older patients or manual laborers with otherwise unremarkable-appearing longitudinal melanonychia.

Next, a case report: Mohs micrographic surgery for recurrent chromoblastomycosis after conventional excision.

This one's a single case, so there's no methods or statistics beat — just presentation, management, and the teaching point. A sixty-six-year-old woman in Pennsylvania, notably with no travel history to an endemic region, developed a shin lesion that biopsy confirmed as chromoblastomycosis, almost certainly from gardening-related splinter inoculation. She was treated with standard five-millimeter margin excision, healed fine, but recurred two years later at the same site. This time, given recurrent disease and her declining systemic antifungal therapy, the authors pursued Mohs rather than repeat conventional excision, specifically to get complete margin assessment. They cleared it in a single stage with a smaller margin than conventional excision would have required, closed linearly, and at eighteen months there's no evidence of recurrence.

The teaching point is squarely about margin assessment philosophy: the authors hypothesize that fungal elements can hide at the margin in conventional bread-loafed sections and seed recurrence, which is exactly the blind-spot problem Mohs is designed to solve. They're upfront that this is essentially the second published case of Mohs for this indication — the first dating back to a Mohs-authored paper from 1986 — so there's no body of evidence here, just a plausible rationale and a reassuring but short follow-up. They also note the patient declined combination antifungal therapy, which is generally considered the most effective approach for this disease, so this is monotherapy-with-surgery data, not a test of surgery alone against the best achievable regimen.

Take-home: this is interesting, not practice-changing. It's a reasonable option to keep in your back pocket for recurrent or anatomically sensitive chromoblastomycosis, particularly when tissue conservation matters or when you're worried a prior excision left fungal elements behind, but it's one case built on one prior case, with under two years of follow-up on a disease that's known to be slow-growing and slow to recur. Don't let this change your default management, but do let it inform a conversation with infectious disease when conventional excision has already failed.

Third, a case report under Communications: occult calvarial defect in a presumed scalp dermoid cyst, a surgical pitfall despite negative ultrasound.

Again, no methods section here — this is presentation, intraoperative finding, and teaching point. A thirty-year-old man had a congenital, slowly enlarging mass at the anterior fontanelle since infancy, not freely mobile over bone. Preoperative ultrasound read as a straightforward lipoma-type subcutaneous lesion with no bony involvement. Intraoperatively, surprise — the cyst extended to the frontal bone, and there was a focal full-thickness calvarial defect exposing, but not breaching, intact dura. Neurosurgery was brought in on the table, the defect was repaired with a gelatin sponge, closure was done with a local flap, and the patient did fine postoperatively, with imaging confirming an intact dura and pathology confirming dermoid cyst.

The teaching point is entirely about preoperative risk stratification for midline congenital scalp lesions. Ultrasound is excellent for characterizing soft tissue but has real limits for detecting bone involvement — that's not a failure of this particular study, it's an inherent limitation of the modality that the authors want you to internalize. The red flags they highlight: congenital onset, midline location, long-standing duration, and especially lack of free mobility over the underlying bone. Any time those features are present, the authors argue for a lower threshold for cross-sectional imaging — CT or MRI — before you pick up a blade, regardless of a reassuring ultrasound. They also flag a nice practical point about radiology communication: explicitly writing "rule out dermoid, evaluate underlying calvarium" on the imaging order can prompt more targeted sonographic technique, though even then ultrasound has ceiling limitations for bone.

Practically speaking, this is close to practice-changing for anyone doing excisions of congenital midline scalp lesions, which includes plenty of dermatologic surgeons doing pediatric or young-adult lesion removal. The actionable change is simple: a negative ultrasound does not rule out an occult calvarial defect in a midline, fixed, long-standing congenital lesion, and that specific constellation should prompt CT or MRI and a low threshold for having neurosurgery on standby, not just on-call.

Last, a Reconstructive Conundrum: reconstruction of a large perioral defect.

This is a technique and decision-making piece, not a data study, so the value is entirely in the reasoning. A seventy-nine-year-old man had a stage one-A melanoma of the right lower cheek excised down to fascia, leaving a sizable defect, just over three centimeters in both dimensions, sitting low on the cheek near the perioral region. The authors walk through the differential of reconstructive options and why each was rejected before landing on their choice.

Skin grafts were dismissed for the usual color and texture mismatch concerns in a cosmetically visible area. A linear repair was considered but felt likely to distort the lip free margin or oral commissure given the defect size. Laterally based cheek advancement or rotation flaps were rejected because the defect's low position would force a horizontal incision across the midcheek — not an ideal aesthetic unit boundary. An inferiorly based V-to-Y advancement was also on the table but would require an incision crossing the mandibular angle, and more importantly, like the rotation and advancement options, it doesn't meaningfully redistribute tension vectors — it just spreads a single vector over more surface area. The critical design constraint throughout is avoiding any lateral tension on the oral commissure and avoiding downward tension on the lower eyelid, since either one risks real functional morbidity — oral incompetence or ectropion, not just a cosmetic miss.

The authors landed on a bilobed transposition flap, reasoning that a single-lobe transposition would still concentrate tension along one bearing line, whereas the second lobe redistributes that tension across a broader arc and can even push counter to the unwanted lateral vector. This is a nice conceptual extension for listeners who associate bilobed flaps reflexively with the nasal tip — the authors explicitly point out the same tension-redistribution logic applies wherever you have a free margin that cannot tolerate distortion, in this case the lip and oral commissure rather than the ala. Technically, this was a standard bilobed design with about ninety degrees of rotation, elevated and inset without tension, closed in layers. At six months, the outcome was described as excellent tissue match with no functional compromise.

The takeaway here is practical and transferable: when you're reconstructing low perioral or lower cheek defects near a free margin, the bilobed transposition flap deserves to be in your differential beyond its usual nasal home, specifically because its two-lobe design lets you redirect and counterbalance tension vectors rather than just distributing a single vector over distance. That's a genuinely useful reconstructive principle to carry into your own perioral and periorbital cases, even though, as a single case report, it doesn't come with outcomes data beyond one patient's result.

That wraps the October issue — a nail melanoma risk-factor study worth filing away for your biopsy threshold conversations, a provocative but preliminary Mohs application in chromoblastomycosis, an important imaging caution for midline scalp lesions, and a sharp reconstructive lesson on redistributing tension near free margins. Thanks for listening, and we'll see you next month.