Ashfaq A. Marghoob, MD, discusses with Keri Holyoak, MPH, MSHS, PA-C, highlights from his 2-part pre-conference lecture on dermoscopy on Wednesday, November 2, 2022, at the PA/NP Elevate-Derm Conference in Tucson, Arizona.

In this video

Dr. Marghoob explains that the real power of dermoscopy lies in examining lesions you've already dismissed as benign. If you only use the dermatoscope on lesions you suspect are cancer, you can improve specificity but not sensitivity — the only way to raise sensitivity is to start looking at the seborrheic keratoses and intradermal nevi that will occasionally reveal "the teeth of the wolf" of melanoma. He also urges clinicians to "monitor biology over morphology": a concerning-looking lesion that isn't evolving can't be cancer, while a benign-looking lesion changing in an irregular fashion speaks strongly for it, which is why serial photography and short- and long-term monitoring matter.

He notes that lentigo maligna, still textbook-labeled a disease of the elderly, is now being caught at 3–5 mm in patients in their 40s and 50s, suggesting it begins as a benign-appearing sunspot decades before it covers half a face — and that earlier detection means far smaller excisions. On volar surfaces, he walks through the ink (gentian violet) test to distinguish furrows from ridges by highlighting the eccrine openings, and the mnemonic "ridges risky, furrows fine." On nail-unit pigmentation, he distinguishes the micro-Hutchinson sign on the cuticle from hyponychial pigmentation, cautioning that a cuticle biopsy can't rule melanoma in or out — you have to go after the matrix.

  • Point the dermatoscope at lesions you think are benign — that's the only way to raise your sensitivity and find melanomas hiding among SKs and intradermal nevi.
  • Monitor biology over morphology: a suspicious lesion that isn't evolving can't be cancer, and a benign-looking lesion evolving irregularly demands a biopsy.
  • Lentigo maligna is being diagnosed at 3–5 mm in patients in their 40s–50s, not just the elderly — earlier detection means smaller excisions.
  • On palms and soles, use the gentian violet ink test to define furrows versus ridges: "ridges risky, furrows fine."
  • Don't rely on a cuticle biopsy (micro-Hutchinson sign) to rule melanoma in or out — an atypical result doesn't exclude melanoma in the matrix, so biopsy the matrix.