Is the acral-lentiginous melanoma (ALM) more malignant than the superficial spreading melanoma (SSM) in a high-risk location? A matched-pair comparison of 113 each ALM and SSM in a multicenter study

Even today, the prognosis of acral-lentiginous melanoma (ALM) remains a controversial topic. We present a large case study including all known factors relevant for prognosis. 113 ALMs in 3616 melanoma patients were paired as precisely as possible with their twins, i.e. with 113 superficial spreading melanomas (SSM) from a group of 619 SSMs with high-risk location. The ALMs and SSMs were equivalent in tumor thickness, patient gender and mode of treatment. The follow-up period was for at least 5 years. The 5-year Kaplan-Meier survival curves in both groups are identical. The poor prognosis often ascribed to ALM results from the prognostic factor location. ALM should therefore be regarded as acral localized melanoma.