Capsule endoscopy versus positron emission tomography for detection of small-bowel metastatic melanoma: a pilot study

Background Melanoma is the most common tumor to metastasize to the GI tract, where it mainly involves the small bowel. Objective To compare capsule endoscopy (CE) and18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET)-CT scanning, the current standard and most sensitive investigation modality, in detecting small-bowel metastases in patients with metastatic melanoma. Design A prospective study of patients with metastatic melanoma who were undergoing FDG PET-CT scanning. CE was performed and the results read by two independent observers without knowledge of the other investigation results. Setting Tertiary care centers. Patients This study involved 21 patients with a median age of 52 years (range 22-88 years). Intervention CE. Main Outcome Measurements Detection of small-bowel melanoma. Results FDG PET-CT scanning showed increased abdominal uptake in 12 patients, but only 5 of these patients were found to have small-bowel melanoma on CE. Importantly, in 1 patient with a bleeding small-bowel tumor on CE, the FDG PET-CT scan result was negative. One patient with positive FDG PET-CT scan results and negative CE results subsequently developed symptomatic small-bowel melanoma 10 months after CE. Limitations Small-bowel melanoma could not be excluded entirely in 7 patients with positive FDG PET-CT scan results and negative CE results, and follow-up is ongoing. The number of patients in this study was small. Conclusion CE was better than FDG PET-CT scanning in localizing small-bowel melanoma. This study suggests that CE is an ideal complementary investigation modality for patients with known metastatic melanoma undergoing preoperative work-ups and in those with unexplained anemia or GI symptoms.