Diagnosis:
Metastatic Melanoma
Comment: Malignant melanoma accounts for one to three percent of all cancers in the United States, but over two thirds of all deaths from skin cancer. It is the most common tumor that metastasizes to the GI tract, accounting for 10% of all metastasis, majority to small bowel (71%), followed by the stomach (27%) , large bowel (22%) and esophagus (5%). The diagnosis of metastatic melanoma to the GI tract is made 1.7% of cases in one study, and another varied from 0.9 to 8.9%.
It can cause a wide variety of gastrointestinal symptoms, which are non-specific: nausea, vomiting, abdominal pain, diarrhea, and weight loss. Small bowel lesions can present with symptoms of appendicitis, malabsorption, and enteropathy. Metastatic melanoma to the GI tract varies after the initial presentation, one case reported 21 years.
Endoscopic examination of the lesions varies from submucosal nodules, polypoid masses, ulceration and large extrinsic tumor mass. They are not necessarily melanotic. Likewise radiologic studies show different presentations: polypoid lesions with or without intussusception, ulcerating lesions with cavitation, diffuse thickening of the intestinal wall or serosal implants. The classic radiologic appearance is that of a bull’s eye, seen when barium fills a central ulcer in the metastatic nodule.
Treatment is aimed at primarily palliation. Surgery is very effective ( 80-90%) in palliating symptoms and improving quality of life. At least 50% of metastatic disease to the GI tract have concomitant disease elsewhere.
Since the incidence of melanoma is increasing, gastrointestinal metastases will be encountered more frequently. Patients with GI symptoms and a history of melanoma should be worked-up thoroughly for the presence of intestinal metastases, regardless of how many years ago the original primary malignancy was diagnosed.
Primary melanoma originating in the gastrointestinal tract is very rare and the majority of these tumors arise in the mucosa of the anus or rectum and occasionally the esophagus.
References:
- Ihde JK, Coit DG, Melanoma metastatic to stomach, small bowel or colon, Am J Surg, 1991 Sep;162 (3) 208-11.
- Adam YG, Efron G. Cutaneous malignant melanoma: current views On pathogenesis, diagnosis and surgical management. Surgery 1983; 93:481-494.
- Backman H. Metastases of malignant melanoma in the gastrointestinal tract. Geriatrics 1969: 24:112-120.
- Blecker d, Abraham S, Melanoma in the gastrointestinal tract. Am J Gastroenterology 1999; 94:3427-3433.
- Goldstein HM, Beydoun MT, Radiologic spectrum of melanoma metastatic to the gastrointestinal tract.