JAAD Comment Sets Biopsy Geometry Rules for Acral Lesions

A comment published in the Journal of the American Academy of Dermatology, Volume 95, Issue 5, dated November 2026, argues that surgeons biopsying acral melanocytic lesions should cut parallel to the dermatoglyphs — and then section the specimen perpendicular to them. Authors Patrick S. Phelan and Sara C. Shalin direct the advice at anyone diagnosing suspicious lesions on palms and soles, where ridge anatomy and histology intersect in ways that can make or break a diagnosis.

The letter is a formal comment on a prior study by Thakker et al. Its core message fits in one line: the orientation of the incision and the orientation of the microtome section are two separate decisions, and conflating them creates diagnostic error.

Why does incision orientation matter on acral skin?

Acral skin is unique. The dermatoglyphs — the friction ridges of the palms, soles, and digital pads — run in predictable lines, and melanocytes there sit in ridge and furrow patterns that pathologists read under the microscope. When a biopsy specimen is cut at the wrong angle relative to those ridges, the histological architecture flattens or distorts.

Phelan and Shalin's proposed workflow resolves this in two moves:

• Incise parallel to the dermatoglyphs when taking the biopsy.
• Section perpendicular to the dermatoglyphs when processing the tissue.

The takeaway in plain words: choose your blade angle and your sectioning plane independently, each to serve the pathologist's view.

What does the comment change?

The authors are responding to Thakker et al., whose work the comment engages point by point. The contribution is procedural rather than therapeutic — no drug, no device, no effect size. It concerns the diagnostic pathway for acral melanocytic lesions, a category that includes the subtype with among the poorest survival outcomes in melanoma, acral lentiginous melanoma, though the comment itself addresses biopsy technique across acral melanocytic lesions generally.

For dermatologists in practice, the practical stakes are concrete. A poorly oriented specimen can obscure the ridge-furrow relationship that helps distinguish benign acral nevi from early melanoma. That distinction drives downstream decisions on re-excision margins, staging workup, and referral.

The section-level takeaway: correct geometric planning at the bedside preserves the histological landmarks the microscope needs.

Where does this fit in the literature?

The comment appears in JAAD's correspondence section, a venue for focused methodological correction and refinement rather than trial results. Phelan and Shalin's argument is a technique argument — about how tissue is taken and how it is cut — directed at both the clinician holding the blade and the laboratory handling the block.

Volume 95, Issue 5 carries a November 2026 publication date, placing the exchange in the current cycle of JAAD correspondence on acral lesion management. Readers who want the full evidentiary context will find it in the Thakker et al. paper the comment addresses, alongside the journal's companion correspondence.

The one-sentence version for the clinic: before you cut, read the ridges — incise with them, section across them.

Whether journals adopt explicit reporting of incision and sectioning orientation in acral biopsy protocols will tell how far this technical argument travels.