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10 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
Acral melanoma grows on the soles, palms or under a nail, places without sun exposure, and it is the commonest melanoma in people with darker skin. It is often mistaken for a wart, bruise or fungal nail and so found late; treatment follows skin melanoma, but immunotherapy works less often because the tumour carries fewer mutations.
Acral melanoma arises on the glabrous skin of the palms, soles and nail apparatus and is not caused by ultraviolet light; its genome has few point mutations but frequent amplifications of CCND1, CDK4 and TERT and other structural changes. BRAF V600 mutations occur in about one in six tumours, NRAS in a similar share and KIT alterations in around one in ten. Delay in diagnosis is the rule, since lesions are mistaken for warts, calluses, haematomas or fungal nail infection, and thick, ulcerated primaries with nodal spread are common at presentation; stage for stage, outcomes are somewhat worse than for other cutaneous melanomas.
Management follows cutaneous melanoma: excision with margins set by thickness, which for digits may mean amputation of the distal phalanx, sentinel node biopsy for primaries over 0.8 millimetres, and adjuvant anti-PD-1 antibody or, for BRAF-mutant disease, dabrafenib-trametinib after resection of stage III disease. Reconstruction of weight-bearing soles is a particular surgical problem. No adjuvant or advanced-disease trial has been run in acral melanoma alone; the evidence is extrapolated from trials in which acral tumours were a small minority.
| Setting | Approach | Guideline |
|---|---|---|
| Diagnosis | Dermoscopy of the parallel ridge pattern and biopsy of any changing pigmented lesion of the palm, sole or nail; nail matrix biopsy for longitudinal melanonychia with Hutchinson sign. | not mapped |
| Localised disease | Wide local excision with thickness-based margins, distal amputation for subungual disease when needed, sentinel lymph node biopsy for primaries over 0.8 mm. | not mapped |
| Resected stage III | Adjuvant nivolumab or pembrolizumab; dabrafenib-trametinib for BRAF V600-mutant disease; neoadjuvant immunotherapy for macroscopic nodes as in NADINA. | not mapped |
| Advanced disease | Nivolumab plus ipilimumab or anti-PD-1 monotherapy; BRAF-MEK inhibitors for BRAF-mutant tumours; imatinib for KIT-mutant tumours; tunlametinib for NRAS-mutant disease in China; trials of CDK4/6 inhibitors. | not mapped |