Gluteal nodules in patients with metastatic midgut carcinoid disease treated with depot somatostatin analogs

Context and Objectives: We were referred a patient with metastatic well-differentiated endocrine tumor of the small intestine (midgut carcinoid) in whom asymptomatic sc gluteal nodules had been identified on routine abdominal computed tomography and labeled as metastases. This prompted us to assess the prevalence and cause of these nodules. Design and Setting: This was a retrospective, cross-sectional study at a university teaching hospital. Methods: Routine abdominal computed tomography scans of 56 patients with metastatic midgut carcinoid were analyzed by two independent radiologists, blinded to treatment status (depot somatostatin analogs). Main Outcome Measures: Number of patients with nodules, number of injections, and duration and total cumulative dose per patient were assessed. Results: No nodules were detected in 13 patients not on depot somatostatin therapy. Nodules were found in 29 of 43 patients (67%) on somatostatin analog therapy: 16 of 22 patients on lanreotide Autogel, five of 12 patients on octreotide LAR only, and eight of nine patients who had been treated with both somatostatin analogs. There was no difference in the clinical state of those with or without nodules. Per patient, the average number was seven, and average size was 1 cm. Presence of nodules was significantly associated with total number of injections (P = 0.024), duration on treatment (P = 0.022), and cumulative dose of lanreotide Autogel (P < 0.001). Nodules underwent involution on follow-up imaging. Conclusion: Patients with metastatic midgut carcinoid tumors have large numbers of asymptomatic sc nodules in the gluteal area when on either depot somatostatin analog, but these resolve over time. This clear observation gives reassurance to patients and those managing them that such nodules are unlikely to represent metastases.