Vertical brown-black nail lines (longitudinal melanonychia): Indications for referral

Any new vertical brown-black nail lines in a fair-skinned patient
Vertical brown-black lines on a single nail, in any patient
Any history of change in the brown-black lines or bands (darkening, widening, bleeding)
Width of brown-black lines greater than 6 mm
Proximal width greater than distal width
Heterogeneous color
Indistinct borders
Associated nail fold pigment (Hutchinson sign)
Associated nail plate dystrophy
Associated bleeding
Associated ulceration
High-risk digit (thumb, index finger, great toe)
Personal or family history of melanoma