The Dark Band on the Thumb Nail
Arun, 42, a school bus driver, comes in for a manicure before his sister's wedding. On his left thumb nail there is a dark brown band about 3 mm wide running from the cuticle to the free edge. It first appeared roughly four months ago and has become wider since; the pigment also smudges onto the skin of the fold at the base of the nail. He wants a gel extension over the thumb 'to hide it' in the photographs. His right index finger is red, hot and throbbing along the side of the nail, with a small yellow collection of pus under the fold; he has been biting a hangnail there for a week. He asks the therapist to 'cut the pus out and clean it properly'. He is otherwise healthy, takes no medicines, and has no other symptoms.
1. Describe the relevant nail anatomy and explain, from the position of the band, why it needs medical assessment rather than cosmetic covering.
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The visible nail plate is dead keratin produced by the nail matrix, which sits under the proximal fold; the pale half-moon (lunula) is the visible part of that matrix. The plate slides forward over the nail bed, sealed at the base by the cuticle and at the tip by the hyponychium, with side folds on either side.
Because pigment is laid down in the matrix and then carried outward as the plate grows, a band running the full length of the nail means the source is in the matrix, and a band 3 mm wide means about 3 mm of matrix is producing pigment. Common causes include a benign melanocytic naevus, racial pigmentation, drug pigmentation and trauma. However, pigment that spills onto the surrounding fold - Hutchinson's sign - is a recognised warning feature of subungual melanoma, because it suggests pigment is spreading into adjacent skin.
A simple blood blister would travel out with the plate and would not stain the fold. A gel extension would hide the very change that needs monitoring, so it must be refused until a dermatologist has assessed the nail.
2. Decide what the therapist may and may not do for the infected finger and for the band, and state the urgency of referral.
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The index finger. Redness, heat, throbbing and visible pus indicate an acute bacterial paronychia. Incising or squeezing is outside a beauty therapist's scope, risks pushing infection deeper into the finger, and can cause permanent nail deformity. The therapist must not cut, pierce, squeeze or apply a manicure to that finger, and should not apply a false nail over it. Refer to a doctor promptly - the same day or next - because an abscess may need drainage and antibiotics; spreading redness up the finger or fever means urgent care.
The thumb band. No gel extension, no buffing, no cuticle work over the pigment, and no reassurance that 'it is only a stain'. Refer to a dermatologist with a written note of what was observed and when it first appeared. This is not an emergency, but it should be seen within days to a couple of weeks, not postponed until after the wedding.
Offer to manicure the remaining nails, with the client's agreement, so the appointment still has value and he is not simply sent away.
3. How would you explain the findings to Arun and record them, without alarming him and without diagnosing?
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Explain in plain language, sitting down, without a diagnosis. Something like: 'Arun, I can do your other nails today. But this dark line and the bit of colour on the skin at the base is something I am not qualified to treat, and covering it with a gel nail would stop anyone watching it. Most lines like this turn out to be harmless, but a change that has widened needs a skin doctor to look at it properly. Here is a note you can show them.'
Recording:
- Date first noticed, size and appearance of the band, involvement of the fold, any change over time.
- The redness, swelling and pus on the index finger, and the advice given.
- That the gel extension and manicure on those digits were declined, and why.
- Client's signature and the referral given.
Do not photograph the nails for the salon's social media without separate written consent, and do not tell him he 'has melanoma' or that he 'has nothing to worry about'. Both are outside the therapist's role and both can harm.