Primary Malignant Melanoma of the Rectum: Long-Term Disease-Free Survival Following Abdomino-Perineal Resection

Objective: Primary Malignant Melanoma (PMM) arising from the digestive, respiratory or genitourinary tract is extremely rare. Rectal PMM accounts for less than 1% of all melanomas; it is often advanced at initial presentation with a poor prognosis with a 5-year survival below 20%. Treatment of this particular disease is still debated with weak evidence that aggressive surgery may lead to a better outcome. The objective of the present paper is to descibe a case of PMM and review the published literature on the treatment of such extremely rare condition. Methods: A 78 years old man presenting mild anal bleeding underwent a colonoscopy which showed a centimetric mass in the posterior wall of the rectum, less than 1 cm above the pectinea line. Biopsy revealed amelanotic malignant melanoma infiltrating the submucosa. Preoperative assessment revealed no distant metastases and no nodal involvement. Abdominoperineal resection (APR) with total mesorectal excision and iliac nodes sampling was performed. Results: the patient is alive and disease-free after 48 months from diagnosis. According to a literature review, APR with or without intra abdominal pelvic lymph node dissection represents a more radical approach in patients seeking curative options. However, some series suggest that wide local excision (WLE) may have similar survival outcomes but seems to be burdened with a higher rate of local recurrences. Conclusions: Our experience confirms that treatment recommendations are not standardized and tend to be individualized. An aggressive surgical approach may be justified in patient with a long life expectancy accepting a demolitive surgery and a definitive colonostomy.