Dermoscopy in skin of colour
Dermoscopy in pigmented skin; dermoscopy in Black, Asian, African and minority ethnic skin
Dermoscopy in Fitzpatrick IV–VI skin is an important equity issue. Acral lentiginous melanoma is proportionally over-represented and frequently presents late in this population; awareness of the parallel-ridge pattern and a low threshold for biopsy of any irregular acral lesion are essential. Common benign mimics — dermatosis papulosa nigra, acral melanocytic naevi with regular parallel-furrow pattern, lichenoid keratoses, post-inflammatory hyperpigmentation — must be recognised. Pigmented BCC may show less obvious arborising vasculature; melanoma in pigmented skin can lack network and show structureless brown areas — different not absent. Routine dermoscopy training disproportionately uses light-skin examples; deliberate effort to learn pigmented-skin patterns is a UK equity priority.
Why it matters — the equity gap
- Although melanoma incidence is much lower in Fitzpatrick IV–VI populations, the proportion of melanomas that are ALM is ~ 40–70% (vs < 5% in Northern European populations).
- Late presentation drives substantially worse stage-matched outcomes — 5-year survival ~ 30% lower in some UK studies for ALM in Black patients.
- Dermoscopy training disproportionately uses light-skin imagery — clinicians need deliberate exposure to pigmented-skin patterns to be confident.
Acral patterns (palms / soles / nails)
- Benign — parallel-furrow, lattice-like, fibrillar patterns; pigment in the narrower furrows.
- Suspicious — parallel-ridge pattern (pigment in the wider ridges) — high specificity for ALM in trained hands.
- Other suspicious features — multicomponent pattern, asymmetric pigmentation, blue-white veil, irregular dots.
- Subungual — longitudinal melanonychia > 3 mm wide, asymmetric colour, Hutchinson sign — refer.
Common benign lesions in pigmented skin
- Dermatosis papulosa nigra — small uniform brown-black facial papules; SK-like dermoscopy.
- Acrochordon (skin tag) — pedunculated, brown.
- Acral melanocytic naevi — parallel-furrow / lattice / fibrillar.
- Post-inflammatory hyperpigmentation — diffuse brown patches, often after trauma.
- Naevus of Ito / Ota — dermal blue-grey patches.
- Acanthosis nigricans, confluent and reticulated papillomatosis — neck / flexures.
Pigmented BCC and pigmented melanoma
- Pigmented BCC is commoner in Fitzpatrick IV–VI than light skin — blue-grey ovoid nests, leaf-like areas, spoke-wheel structures.
- Arborising vessels may be subtle or obscured by pigmentation — supplement with palpation and clinical history.
- Pigmented melanoma can lack a typical pigment network; look for structureless brown areas, multiple colours, peripheral irregularity.
- Always combine dermoscopy with clinical context (asymmetry, change, location, ulceration, ABCDE).
Practice recommendations
- Use dermoscopy training resources that include pigmented-skin images — Skin of Colour Society, BAD diversity resource, Mind the Gap (St George's, London).
- Lower threshold for biopsy of any acral pigmented lesion that does not show a typical benign parallel-furrow / lattice / fibrillar pattern.
- Photograph and document baseline appearance of pigmented lesions — change over time is the most reliable signal.
- Counsel patients about self-examination — particularly acral, oral, genital and nail surveillance.
References
- Saida T et al. Significance of dermoscopic patterns in detecting early acral lentiginous melanoma. J Am Acad Dermatol; 2004.
- Madankumar R et al. Acral melanocytic lesions in the US — skin-colour-specific dermoscopy. J Am Acad Dermatol; 2016.
- Mind the Gap (St George's, London) — pigmented-skin clinical reference.
- Skin of Colour Society — dermoscopy resources.
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