A Dark Band on One Thumb
A 58-year-old client sits down for a gel polish manicure. On the left thumbnail you see a single 2 mm brown-black band running from beneath the proximal fold to the free edge. The borders are slightly blurred, the color is uneven, and no other nail is affected. The surrounding skin looks normal. She has been a hairdresser for 30 years and her hands are often wet. She says, “My father had a dark nail for years and never worried about it.” She takes a blood thinner for a heart condition and mentions a “funny feeling” in the fingertip but no pain. No trauma, no picking, no previous nail surgery. She wants gel polish to “cover the streak” before a family reunion in four days and offers to sign anything you want.
1. What does this finding suggest, and what do you do about the service? Explain the reasoning behind each decision.
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What it is. A single, 2 mm brown-black band running from the proximal fold to the free edge on one thumb in a 58-year-old, with blurred borders and no trauma history, is longitudinal melanonychia. Most cases are benign - a benign nevus, a lentigo, medication or pigment - but a new single band in an adult is the presentation that has to be checked for subungual melanoma. Blurred borders, a band that widens over time, and pigment spilling onto the proximal or lateral nail fold (Hutchinson's sign) raise the level of concern. The family history she offers is not reassuring evidence either way; “never worried about it” is not a diagnosis.
Do not service that nail. No gel polish, no buffing, no aggressive cuticle work that pushes pigment or opens the fold. Covering it hides changes the physician needs to see, and abrading the plate disturbs the tissue being evaluated. Diagnosing it is outside your scope; noticing and referring is squarely inside it.
Refer specifically. “This needs to be seen by a doctor - a dermatologist is ideal, and soon rather than in a few months. It isn't something I can cover.” Do not say “cancer,” and do not soften it into “probably nothing.” Put the referral in the record.
The rest of the service. You can manicure and polish the other nine nails if she wants. The thumb stays untouched.
2. How would you distinguish this from a subungual hematoma or splinter hemorrhages caused by trauma? List the history questions you would ask and how the answers change your decision.
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Subungual hematoma is a pool of blood under the plate from a blow. The client remembers the injury - a door, a drawer, a dropped weight. Color is red-purple to black, often with a ring of discoloration, and it migrates out with the plate as the nail grows. It does not present as a stripe running from under the proximal fold.
Splinter hemorrhages are thin dark longitudinal lines in the distal third, often several per nail. Very commonly traumatic - aggressive filing, tapping, occupational pressure - but multiple nails with no trauma history deserve a medical comment rather than a shrug.
Questions. Did you injure it? When? Has the mark changed shape, widened, or darkened since you first noticed it? Is there any pigment on the skin around the nail? Any new medications? Any other nails like this? Has a doctor ever looked at it?
How the answers change the plan. Clear trauma plus a lesion that grows out predictably - you may service gently and document. No history, a single digit, blurred borders, or pigment on the fold - refer and leave it alone. When the answers are mixed, treat it as the higher-risk picture; the cost of an unnecessary referral is a co-pay, and the cost of the opposite mistake is much higher.
3. She insists on the gel polish and offers to sign a release. How do you handle the refusal, the documentation, and the follow-up?
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Refuse once, clearly, then offer options. “I understand you want it covered for the reunion, but I can't put product over a mark I can't identify. If it's something that needs treatment, covering it delays that, and I'd be the one who hid it.” Then give her something to say yes to: gel polish on the other nine nails, a shape and tidy on the cuticles of that hand with the thumb left alone.
The release. A signed form does not convert a clinical judgment into a client choice. You are the licensee; the standard of care is yours, not hers. A document signed because she wants a service does not change what you already saw.
Document. Size, location, color, blurred border, absence of trauma, family history, the “funny feeling” she described, that you explained your concern, that you referred her, and that she asked you to cover it and you declined. Date it.
Follow up. A brief message in two weeks asking whether she was seen is good practice, not overstepping - it also closes the loop professionally. If she returns with physician clearance, service the nail normally, and note the clearance.