The Band on the Thumb: Buff It Out or Refer It?
A 47-year-old man comes in for his first manicure before a job interview. On the left thumbnail there is a dark brown-to-black band about 3 mm wide running from the cuticle to the free edge. The pigment appears to extend onto the proximal nail fold, and the cuticle line is less distinct on that side. He says it "showed up" about five months ago and thinks he slammed the thumb in a car door around then, though he is not certain. He is otherwise well, takes no medications, and has no similar bands on other nails. Several other nails show faint horizontal grooves. He asks you to "buff it out."
1. Do you perform the manicure as requested? What do you do about the band?
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No buffing. Pigment in a band like this is in the nail plate and matrix, not a surface stain, so buffing removes nothing and only thins the plate. Aggressive cuticle work at that fold is also off the table.
Several features argue for referral rather than reassurance: it is new, it is a single digit, it is a longitudinal band about 3 mm wide with blurred margins, and pigment appears to involve the proximal nail fold - that last sign is the one that makes a clinician want to look at it promptly, because a new pigmented band with fold involvement needs evaluation to rule out subungual melanoma. A bruise usually has a matching injury history, moves out with the nail, and does not stain the fold. You cannot tell the difference by eye, and you do not diagnose.
So: recommend a dermatologist appointment soon, and say why in plain language. A gentle manicure on the other nails is fine; on the thumb, limit to cleaning, shaping, and light cuticle care without cutting or trauma.
2. How do you phrase the referral and what do you document?
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Phrase it as a recommendation, not a diagnosis: "I can't diagnose this, and I'm not going to try to buff it out because the color is inside the nail. A new dark band that reaches the cuticle line should be looked at by a dermatologist, and I'd get it on the schedule rather than wait." Avoid "it's probably cancer" and avoid "it's just a bruise" - both are guesses.
Document objectively: digit, band width, color, margins, extent toward the fold, onset as reported, the reported trauma and the uncertainty around it, the appearance of other nails, that the service was modified and no buffing was done, that a dermatologist referral was advised and why, and whether he accepted it. If salon policy allows and he consents, a photo with a date is useful for comparison. Note if he declines the referral.
3. What do you make of the horizontal grooves on the other nails, and does that change anything?
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Faint transverse grooves on several nails are consistent with Beau's lines - a temporary interruption in matrix activity, often after a fever or illness, sometimes from trauma or medication. On their own they are not a reason to refuse a manicure and they grow out. They can be lightly smoothed.
They do not change the urgent action, which is the pigmented band. They do add a reason to ask a general question about recent illness or new medications, and if grooves are deep, recurring, or present with other new nail changes, suggest he mention everything to the doctor at the same visit.
The judgment point is prioritization: do not let a minor cosmetic finding distract from the one finding that warrants prompt medical evaluation. Keep the two separate in your notes so the record is clear about what triggered the referral.