Difficulties in diagnosing anorectal melanoma: A case report and review of the literature

Abstract

BACKGROUND Anorectal melanoma is a tumour that is difficult to identify due to its rarity and variability of presentation. Insufficient data published in the literature do not allow for diagnostic and treatment guidelines to be established. Anorectal melanoma has the worst prognosis among mucosal melanomas and is frequently misdiagnosed by standard identification methods. CASE SUMMARY A 66-year-old woman presented with intermittent anal bleeding, pain, and tenesmus in the past month, with no associated weight loss. Colonoscopy revealed a cauliflower-like tumour with a diameter of 1.5 cm, with exulcerated areas and an adherent clot but without obstruction. Biopsy results identified an inflammatory rectal polyp with nonspecific chronic rectitis. Tumour markers CA 19-9 and CEA were within the normal range. After 6 mo, due to the persistence of symptoms, a pelvic magnetic resonance imaging scan was performed. A lesion measuring 2.8 cm × 2.7 cm × 2.1 cm was identified at the anorectal junction, along with two adjacent lymphadenopathies. No distant metastases were detected. Immunohistochemistry was performed on the second set of biopsies, and a diagnosis of anorectal melanoma was established. Surgical treatment by abdominoperineal resection was performed. Evolution was marked by the appearance of lung metastases at 1 mo postoperatively, detected on a positron emission tomography-computer tomography scan, and perineal recurrence after 5 mo. After molecular testing, the patient was included in an immunotherapy trial. CONCLUSION This case highlights the difficulty of establishing a definitive early diagnosis of anorectal melanoma, the importance of performing histological analysis on a well-represented biopsy specimen, and the poor prognosis, even with radical surgery.

Management of primary anorectal mucosal melanoma during the COVID-19 pandemic

“…The difference in failure and recurrence rate between the two procedures is minor at best; some studies do not show a significant advantage between the two [ 5 , 8 , 16 – 19 , 30 – 33 ]. In addition, less radical endoscopic mucosal resection has been described for less advanced cases [ 34 ].…”

“…Resection of lymph nodes is controversial, as it can increase complications [ 34 ]. The mesorectal, pelvic sidewall and inguinal lymph nodes are the most likely to be involved [ 29 ], but it is unclear whether the involvement or removal of these nodes improves the prognosis.…”

“…The mesorectal, pelvic sidewall and inguinal lymph nodes are the most likely to be involved [ 29 ], but it is unclear whether the involvement or removal of these nodes improves the prognosis. Therefore, some recommend lymphadenectomy only for palpable or regional nodal disease [ 34 ].…”

“…Given these observations, our desire to quickly achieve local control, local surgical expertise, patient preference and tumour extent and recurrence, we chose APR with lymph node excision because the lesion was extensive, had infiltration greater than 4 mm [ 4 ], had poorly defined edges and had recurred. This decision has precedent in the literature, as a Stage IIIA case achieved good local control with similar surgery [ 34 ]. We recognise that this procedure has lifelong consequences for the patient, but we felt that this choice was best because it eliminated the primary tumour.…”

Clinical and Imaging Research in the Diagnosis of Anorectal Melanoma with Surgical Outcome: A Case Report and Literature Review

“…Patients with recurrent or metastatic disease have a median survival rate of less than 10 months. [1][2][3]…”