Final answer:
Metastatic melanoma is the most likely cause for small bowel obstruction in a patient with a history of melanoma.
Step-by-step explanation:
The most likely cause of small bowel obstruction (SBO) in a patient with a history of melanoma would be metastatic melanoma. Melanoma is a type of skin cancer that is highly aggressive and has the tendency to metastasize to other parts of the body, including the small bowel. When melanoma cells spread to the small intestine, they can cause a blockage and lead to SBO.