Primary melanosarcoma of the rectum.

We report two cases of anorectal malignant melanoma observed these last four years in the department. The first case was a 62-year-old female patient, and the second case was a 68-year-old male patient. Both suffered from a primary rectal tumour, arising from the rectum, with an intact anal canal. There were pulmonary metastases in the latter patient. At rectal biopsies, tumours were poorly differentiated and diagnosis of malignant melanoma could only be established by the complementary immuno-histochemical methods. The first patient had an AP excision of the rectum and died from generalized disease seven months later. In the second case, only palliative irradiation was carried out and the patient died six weeks later. Literature review confirms that rectal melanoma is a very rare tumour. Diagnosis is difficult, especially in the amelanotic forms. Prognosis remains very poor and the best therapeutic approach is still controversial.