Malignant melanoma is the most dangerous type of skin cancer. Melanomas beneath the fingernail appear as a black or bluish black discoloration. This type of malignancy spreads (metastasizes) readily.
Review Date 1/21/2020
Updated by: Michael Lehrer, MD, Clinical Associate Professor, Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.