What should you know about subungual melanoma nail?

Subungual melanoma develops in the nail unit, often causing a brown or black band that begins near the cuticle and extends along the nail. The colour may become wider, uneven or varied. Pigment can spread onto nearby skin around the nail, a finding called the Hutchinson sign. A split, lifting nail, bleeding, soreness or a persistent mark without a clear injury also deserves attention. Many nail marks have harmless explanations, so appearance alone cannot confirm melanoma. A clinician may examine the nail with dermoscopy and compare it with the other nails.

Arrange a dermatology appointment promptly if a new or changing streak is present. Bring photographs showing when the change began, and mention trauma, medicines, family history of melanoma and any previous skin cancers. The clinician may recommend a biopsy of the nail matrix or nail bed; laboratory examination of tissue is what establishes the diagnosis. If melanoma is confirmed, staging guides the discussion about surgical excision, possible sentinel lymph node biopsy and other care. Learn more about [Melanoma](/conditions/melanoma/), [Surgical Excision](/treatments/surgical-dermatology/excisional-surgery/) and [Sentinel Lymph Node Biopsy](/treatments/diagnostics-and-staging/sentinel-lymph-node-biopsy/).

Seek prompt medical assessment for a dark streak that is new, changing, widening or spreading onto the surrounding skin. Do not wait for pain: early nail-unit melanoma may have little discomfort. Seek urgent care if the nail is bleeding repeatedly, rapidly changing, badly swollen or associated with a new lump. Sudden severe pain, pus or fever may point to infection or injury and also needs medical attention.

Could this mark be caused by injury, a mole, infection or melanoma? Do you recommend dermoscopy or a biopsy, and which part of the nail will be sampled? How will the result affect staging and treatment? What nail changes should prompt an earlier review?