What is Subungual Melanoma?
Subungual melanoma is a type of melanoma that develops in the nail matrix—the tissue under the nail that produces the nail plate. It accounts for about 0.7-3.5% of all melanomas but has a higher percentage in people with darker skin.
Because it's hidden under the nail, subungual melanoma is often diagnosed at a later stage than other melanomas, making awareness crucial. The classic sign is a dark longitudinal streak running from the cuticle to the nail tip.
Warning Signs
See a dermatologist if you notice:
Benign vs Concerning Nail Streaks
| Feature | Likely Benign | Concerning |
|---|---|---|
| Streak width | Stable, narrow (<3mm) | Widening, >3mm |
| Color | Uniform brown | Multiple colors, very dark |
| Borders | Sharp, regular | Irregular, blurred |
| Hutchinson's sign | Absent | Present (pigment on skin) |
| Change over time | Stable for years | Growing, darkening |
| Number of nails | Multiple nails similar | Single nail affected |
What is Hutchinson's Sign?
Hutchinson's sign is when the dark pigment from a nail streak extends beyond the nail onto the surrounding cuticle, nail fold, or fingertip skin. This is a critical warning sign that strongly suggests melanoma.
If you notice pigmentation spreading from the nail onto the surrounding skin, seek urgent dermatological evaluation. Hutchinson's sign is considered highly suspicious for subungual melanoma.
Frequently Asked Questions
Medical Disclaimer
This article is educational only. Only a dermatologist can diagnose subungual melanoma through biopsy. Seek professional evaluation for any concerning nail changes.