A pilot study of extralevator abdominoperineal excision for primary melanoma of the anorectum

Melanoma of the anorectum represents < 2 % of all anorectal cancers and 0.3 % of all primary melanomas. Prognosis is poor, and optimal surgical management is controversial. This series details the surgical management of patients with anorectal melanoma presenting between 2002 and 2013 to the Queen Elizabeth Hospital in Birmingham, UK, a tertiary referral centre for colorectal disease. A retrospective review of patient notes, histology reports, and clinical letters was used to assess perioperative course and long-term outcome of all surgical methods. Eight patients with a median age of 65.5 presented with primary anorectal melanoma during the study period. Six cases were staged as T4 pre-operatively, with two referred as incompletely excised polyps. All eight patients underwent abdominoperineal excision of the rectum (APER), with the most recent four cases undergoing extralevator APER. Clear resection margins were achieved in three out of the four patients in the extralevator APER group with no nodal spread detected at histological assessment. Extralevator APER appears to be feasible and safe in the treatment of melanoma of the anorectum, with 75 % medium-term survival (median 38 months) in selected patients. As it is known that clear margins at surgery are associated with disease-free survival, the wider excision margin at the level of the pelvic floor offered by extralevator APER could result in more favourable surgical outcomes in this prognostically poor malignancy.