Malignant melanoma of the gastro-intestinal tract: a case series.

Background: Resection of gastrointestinal (GI) metastases of malignant melanoma (MM) offers a significant survival benefit. No adjuvant therapy has been shown to be effective in the treatment of these metastases.

Methods: All resections of MM affecting the GI tract at a UK University teaching hospital between October 1999 and January 2013 were identified from a pathology database. Demographic, investigative, operative and outcome data were retrieved from hospital records. Survival analysis was performed.

Results: Thirty patients were identified (median age 62.7 years). 3 patients underwent a second operation at a later date to resect further metastases. 6 patients (20.0%) presented with no identifiable cutaneous lesion. The average time to GI metastases was 52.0 months (range 4.9-139.8 months) for those with an identified cutaneous primary (n = 24). Two patients with initial cutaneous lesions with Breslow's thickness <1 mm developed GI metastases. Common presenting symptoms included abdominal pain (n = 8, 27.6%), GI bleeding (n = 5, 17.2%) and symptoms of GI tract obstruction (n = 4, 13.8%). CT scan was the most commonly performed investigation (96.6%). Over half of resections (54.5%, n = 18) included small bowel resection. Mortality at 2 and 5 years was 66.4% and 73.1%. Of the 3 patients who underwent a second resection of GI metastases, one is still alive after 26 months of follow up; 2 patients died after 32.8 and 18.6 months.

Conclusions: Clinicians should have a low threshold for investigating GI symptoms in patients with a history of malignant melanoma even in the case of early-stage primary disease. Re-resection should be considered in patients presenting with further GI metastases.