Malignant melanoma metastasis to the colon: a curable lesion

Metastatic melanoma has a very poor prognosis, with a median survival for patients with stage IV disease ranging from 6 to 18 months [1]. Gastrointestinal tract involvement in melanoma is rare and often represents advanced, disseminated disease [2]. However, more than 50 % of patients with localized metastatic melanoma are amenable to surgery and have a better survival rate than patients who receive non-surgical therapy after metastasectomy. A 78-year-old man presented with a symptomatic right necrotic colonic mass and went on to have a laparoscopic right colectomy for a presumed adenocarcinoma, 41 months after a wide local excision of a malignant melanoma on his forehead. Histology of the excised specimen demonstrated a metastatic malignant melanoma to the colon with clear resection margins. Seventeen lymph nodes were identified, and all were negative for metastasis. The patient’s postoperative course was uneventful, and he was discharged on day 4. Subsequent careful skin examination, computed tomography of the thorax, abdomen and pelvis, cerebral computed tomography, and positron emission tomography demonstrated no evidence of persistent neoplastic disease. The most frequently involved portion of the gastrointestinal tract is the small bowel (in about 91 % of cases) [3]. The difficulty of achieving curative resection in cases of small bowel metastasis probably explains the low survival rates that are observed in the literature. However, prolonged survival has been reported in case of isolated metastasis to the colon. In a case series from the Mayo Clinic Scottsdale and a review of the literature published in 2003, Tessier et al. [4] found that the average time interval between diagnosis of the primary and metastatic disease to the colon was 7.47 years. The most favorable prognostic factors are a complete resection of the colonic metastasis, the absence of colonic perforation or obstruction, the absence of residual intra-abdominal disease, the absence of extra-abdominal metastases, and a disease-free interval longer than 24 months [5]. A colonic tumor in a patient with a history of resection of a malignant melanoma should be considered to be not just a colonic carcinoma, but also a metastasis of the melanoma, even several years later. We would like to emphasize the fact that surgical resection of the metastasis, if it is a single lesion, is the best strategy to improve survival.