Synopsis
Read nail morphology as a diagnostic clue without overclaiming specificity, recognise melanoma and infection warnings, and connect psoriasis, clubbing, koilonychia and other changes to proportionate investigation.
- Nails record matrix, bed and systemic events slowly; name the structure and pattern before assigning a disease, because most single signs are not specific.
- Psoriasis causes regular pitting, oil-drop or salmon patches, subungual hyperkeratosis and onycholysis with an erythematous border, and may exist without obvious skin plaques.
- A new evolving irregular longitudinal melanonychia band in one adult nail, especially with periungual Hutchinson pigment or nail destruction, must be assessed urgently for melanoma.
Key red flags
A new or changing single-nail longitudinal pigmented band with irregular width or colour, proximal widening, Hutchinson sign, nail dystrophy, bleeding, ulceration or a subungual mass requires urgent suspected melanoma assessment.
A new single band with irregular lines, colour variation, proximal widening, periungual extension or dystrophy raises nail-unit melanoma concern.
Investigation priorities
Define number, symmetry, anatomical structure and associated skin or joint phenotype.
Management branches
Longitudinal brown or black pigment appears in one or more nails.
- Ask onset, change, trauma, medicines, pregnancy, family pigmentation and melanoma history, then examine every nail, skin and mucosa and photograph with consent.
- Refer urgently a new or changing irregular single band, proximal widening, Hutchinson sign, dystrophy, bleeding or mass through the suspected melanoma pathway.