Welcome back to the journal review. This is the May twenty twenty-six issue of the Journal of the American Academy of Dermatology, and we've got four pieces for you this time — a letter with a nice bit of bench-top engineering, two entries from the Ethics Journal Club, and a substantial clinical review on nail disorders that I think is genuinely high-yield for anyone doing procedural work on the digit. Let's get into it.

First up is a letter to the editor — a notes and comments piece responding to a previously published technique for a homemade negative pressure drainage device. You'll recall the original concept: take a larger syringe as the collection reservoir, and use the plunger rod from a smaller syringe, retracted and fixed in place, to generate and maintain the vacuum. Cheap, resourceful, exactly the kind of thing that gets shared at tumor board or on rounds when a commercial closed-suction drain isn't readily available. This group, writing from plastic surgery departments in China, isn't proposing a new concept so much as fixing a mechanical flaw in the original assembly. Their critique is worth understanding because it's purely biomechanical. In the original configuration, the small syringe's plunger tip — the conical black rubber tip — sits against the flange of the large syringe, with the two thumb pads butted against each other. The problem is that the thumb pads are different diameters, so the center of the small one doesn't even sit within the footprint of the large one. Combine that with the conical tip not seating flush against a flat flange, and you get a mechanically unstable joint — one prone to slipping, snapping, or having the small plunger pop out entirely once real negative pressure and drainage volume are behind it, even with tape reinforcing it.

Their fix is a reverse assembly. Instead of tip-to-flange, they flip the small syringe around so its plunger tip presses against the large syringe's thumb pad, and its own thumb pad rests against the large syringe's flange. Because the small tip is narrower than the large thumb pad, it can seat against roughly a quarter of that surface — a much more concentric, stable interlock, which they describe as a "one-plus-two" configuration using two small plunger rods per large syringe rather than one. They report this holds up under higher negative pressure and larger fluid volumes, and they show it scaled two ways — a 20 milliliter syringe paired with two 2 milliliter plungers, and a 50 milliliter syringe paired with two 5 milliliter plungers — so you can size the device to the wound. They also give a practical pearl on the drainage tubing itself: if you're using a soft intravenous infusion line rather than a stiffer infusion-set hose, cut your side holes only on one aspect of the tube, because holes on both sides of a floppy hose let it collapse under suction; the stiffer infusion-set tubing can tolerate bilateral fenestration for more multidirectional drainage. There's no clinical outcomes data here — this is a fabrication and engineering letter, not a trial — so the takeaway is purely a practical one for anyone building these homemade drains in a resource-limited setting or just out of convenience: orient the small plunger tip against the large thumb pad, not the flange, and match your fenestration pattern to the stiffness of whatever tubing you're improvising with.

Next, two entries from the Ethics Journal Club, both written in that Dear Dr Dermatoethicist advice-column format, so there's no methods or results scaffolding here — just a question and a principle-based discussion.

The first addresses dermatology residents rotating through private practice as part of training. The framing question is whether there's an ethical tension in sending trainees into a fundamentally business-oriented setting for educational purposes. The piece notes that although most residencies are academically anchored, most graduates ultimately land in community or private practice, and interestingly, one survey found residents' stated interest in private practice climbed from about half before residency to roughly two-thirds during training, often tracking financial pressure and student debt. The ethical tension they lay out is a fairly clean beneficence-versus-nonmaleficence argument. On the beneficence side, private practice exposure gives residents a realistic preview of the workflow, patient population, and efficiency demands they'll likely face after graduation — arguably better preparation than an all-academic pipeline provides. On the nonmaleficence side, the concern is that a productivity-driven private practice environment, with a supervising physician under quota pressure, may compress the teaching moment — less time for a broad differential, less time refining procedural technique — potentially producing a thinner educational experience for a trainee who's still building clinical judgment. Their proposed resolution isn't a ban or a mandate either way — it's structural. They suggest elective, ideally final-year, private practice rotations for programs that don't already have them, transparent up-front disclosure during the match process about what any private practice affiliation actually entails contractually, and structured feedback loops from residents and participating private practices to keep the arrangement honest. The phrase they land on is "gown-and-town" partnerships — the idea being that thoughtfully structured exposure to both worlds, rather than exclusive immersion in one, produces the best-prepared graduate.

The second ethics piece is more relevant to those of us doing tumor-focused work, and it's really a case study in how to counsel a patient when you, personally, are one of the data points in a conflicting literature. The scenario: a clinician has a patient with a rare adnexal malignancy, no real guidelines exist, an outside group has published data suggesting sentinel lymph node biopsy has prognostic value in this entity, and the clinician's own prior published research — in a similarly designed, similarly sized, single-center retrospective series — found no such correlation. How do you counsel the patient in front of you when you're both the treating physician and an author with a stake in one side of the conflict? The column's central concept is allegiance bias — the well-documented tendency for researchers to unconsciously weight their own findings more heavily than competing data — and the discussion explicitly invokes the "decline effect," the pattern where early, smaller studies in a sparse field often get walked back or contradicted as more data accumulates, which is offered as a reason for humility here given both studies are retrospective, single-center, and similarly small. The ethical prescription is a fairly concrete checklist rather than an abstract principle: disclose your own conflict of interest as an author up front, summarize the state of the evidence for the patient in plain language without leaning on your own data as the tiebreaker, frame sentinel node biopsy as a genuine risk-benefit conversation — weighing surgical morbidity and treatment delay against an unproven prognostic payoff — and mention imaging surveillance alternatives like nodal ultrasound for patients who'd rather forgo the procedure. They also explicitly recommend multidisciplinary tumor board input, including Mohs surgeons, surgical oncology, and radiation oncology, specifically as a bias-mitigation strategy, not just a staging exercise. There's no new clinical data in this piece — it's a framework, not a trial — but the practical takeaway for anyone managing a rare cutaneous adnexal tumor with sentinel node uncertainty is concrete: disclose your own authorship stake explicitly to the patient, present the conflicting literature symmetrically, and lean on tumor board precisely because it dilutes any single investigator's allegiance bias.

Now to the main course — a clinical review on the evaluation and management of mechanical and structural nail disorders, from a multi-institutional group including Shari Lipner's team at Weill Cornell. This is a review, so there's no methods-and-results arc; it's a synthesis of mechanism, clinical recognition, and management, and it's dense, so I'll walk through its actual structure.

The organizing thesis, stated right up front, is that physical trauma — not onychomycosis — is the leading cause of toenail onychodystrophy, and the review cites that over nine in ten cases of traumatic onychodystrophy have an identifiable underlying foot or toe structural abnormality driving it. The clinical problem they're addressing is that structural and biomechanical contributors are rarely on our differential when we see a dystrophic toenail — we reach for onychomycosis or nail psoriasis first — and the review's central teaching point, which they put in their capsule summary, is that if you treat the fungus or the psoriasis but never address the underlying mechanical driver, the dystrophy can persist or recur regardless of how well you treated the comorbid diagnosis.

They start with basic biomechanics of footwear. Ideal shoes need arch support, secure fastening, and a wide, deep toe box with a heel height under roughly thirty to thirty-five millimeters — beyond that, forefoot trauma escalates. They give a nice bedside maneuver, the toe-to-toe sign, where you place the patient's shoe toe-to-toe against their actual weight-bearing foot to visually demonstrate a mismatch in width — a good patient-education tool when you're trying to explain why their shoe, not their nail, is the problem. And they note the great toenail bears something on the order of two and a half times body weight during normal gait, which climbs further with athletic activity, which is why lateral, anteroposterior, and superoinferior footwear constraints all show up later as distinct mechanical insults with characteristic nail findings, all laid out in their table.

Then they walk through the individual disorders, and this is really the meat of the review for our purposes. Frictional onycholysis gets the most attention — nail plate separation from repetitive minor trauma, worse in toenails from what they term asymmetric gait nail unit syndrome, where a limb-length or biomechanical asymmetry drives repeated friction, subungual hyperkeratosis, and medial nail plate bending that mimics onychomycosis convincingly enough that they flag fleeting back pain as an associated clue pointing you toward a biomechanical rather than infectious cause. Practically, they emphasize that monodactylous onycholysis without an obvious cause should raise concern for subungual neoplasm — worth a radiograph to exclude exostosis and a low threshold for biopsy to exclude squamous cell carcinoma or amelanotic melanoma, and they note that clipping back the onycholytic plate to directly visualize the bed, plus nail plate histopathology, helps sort out onychomycosis, psoriasis, and onychomatricoma when the picture is ambiguous. Management is conservative — regular trimming, avoiding aggressive subungual cleaning, keeping the bed dry, properly fitted footwear or orthoses, and topical sodium hypochlorite if there's a green nail Pseudomonas component.

They move through a cluster of related friction-driven pigmentary and structural changes — frictional longitudinal melanonychia, typically medial hallux or lateral fifth toe from lateral shoe constraints, which may fade in lighter skin phototypes but rarely resolves spontaneously in darker skin; frictional leukonychia from disturbed matrix keratinization; and disappearing nail bed, which they describe as a consequence of prolonged onycholysis removing the nail plate's counterpressure, letting the distal pulp migrate dorsally and the bed atrophy — a good reminder that longstanding onycholysis isn't just cosmetically inert, it can structurally remodel the digit tip over time.

There's a well-organized section on the Beau's lines, onychomadesis, retronychia spectrum, framed as a shared pathophysiology of interrupted nail plate production along a severity gradient. Retronychia is the one worth flagging for a surgical audience — proximal nail plate ingrowth into the proximal fold, presenting as chronic proximal paronychia with an absent cuticle and a thickened, slow-growing, often yellow nail, notoriously prone to being misdiagnosed and mistreated as infection. Ultrasound can confirm a thickened plate stacking beneath the proximal fold, though they're honest that this requires specialized radiologic expertise and isn't done often in practice. Management is staged: early or moderate paronychia without septic granulation gets conservative measures — avoiding prolonged sock-wear, debridement, taping to offload the plate, corticosteroids for fold inflammation — while late-stage disease with proximal plate elevation and intense paronychia moves to definitive plate avulsion, whether surgical, chemical with salicylic acid or urea, or carbon dioxide laser, and they're candid that recurrence is common regardless of approach.

The review closes out this excerpt with onychophosis and subungual heloma, both hyperkeratotic responses to chronic mechanical pressure from footwear and toe malalignment, and both carrying amelanotic melanoma, subungual squamous cell carcinoma, verruca, and exostosis on the differential — reinforcing the review's throughline that any of these mechanical diagnoses still needs biopsy or imaging to exclude malignancy when the presentation isn't classic. They then transition into the structural hand and foot abnormalities themselves — Morton's toe, hallux valgus, hallux rigidus, flat and splay foot — as the anatomic substrate underlying everything just discussed.

The practical takeaway here is genuinely practice-relevant, not just interesting. For a Mohs and dermatologic oncology practice, the biggest actionable point is diagnostic: any dystrophic, onycholytic, or hyperkeratotic toenail — especially monodactylous, especially in an older patient with a foot deformity — warrants a look at gait, footwear, and toe alignment before you anchor on onychomycosis or before you biopsy assuming malignancy is the only differential; and conversely, atypical or refractory presentations still need histopathology or imaging to rule out squamous cell carcinoma, amelanotic melanoma, or exostosis before you attribute everything to mechanics. The retronychia and disappearing nail bed sections are worth bookmarking specifically because those are the ones most likely to be mismanaged as recalcitrant infection rather than recognized as a mechanical process with a defined, if recurrence-prone, treatment ladder.

That wraps up this month's four articles — a practical fix for a homemade drainage device, two ethics columns on training exposure and on managing your own conflict of interest in rare tumor counseling, and a comprehensive nail mechanics review worth keeping on hand the next time a dystrophic toenail doesn't quite fit the fungal or psoriatic script. Thanks for listening, and we'll see you next month.