Value of Gallium-68 Dotatate PET Scan in staging patients with appendiceal carcinoid tumour: a case series.

Objectives To evaluate the value of Gallium-68 Dotatate PET scan in staging patients with appendiceal carcinoid tumour.

Methods A retrospective study was conducted of all patients with incidental appendiceal carcinoid tumours staged with a Gallium-68 Dotatate PET scan in a major tertiary referral hospital between 2011 and 2014. Patients with known current metastatic disease were excluded. Results of scans were compared to histopathology reports.

Results Thirty-two patients with appendiceal carcinoid tumours who had a whole body Gallium-68 Dotatate PET scan were identified. Twenty-three patients were female and nine were male. Median age was 33 years old (12-74). Twenty-six patients had staging Gallium-68 Dotatate PET scan post appendicectomy. Six of those patients proceeded to right hemicolectomy post negative Gallium-68 Dotatate PET scan. Of these 6 patients, 4 had no evidence of residual disease and 2 patients had 1/23 and 1/17 lymph nodes involved respectively. Three patients had incidental appendiceal carcinoid tumour diagnosed on appendicectomy and had right hemicolectomy prior to staging Gallium-68 Dotatate PET scans. Three other patients had incidental appendiceal carcinoid diagnosed post right hemicolectomy for other reasons. There were no positive Ga-68 Dotatate PET scans in all 32 patients irrespective of tumour’s histopathological features.

Conclusions The overall yield of Gallium-68 Dotatate PET scan for staging patients post appendicectomy +/- hemicolectomy found to have appendiceal carcinoid tumour is very low. This is irrespective of tumour size or other histopathology features. This may reflect the low disease burden in these patients. Our study does not support the use of Gallium-68 Dotatate PET scan for staging of incidental appendiceal carcinoid tumours.