Background: Somatostatin receptor PET/CT with 68-gallium–labeled tracers (e.g., 68Ga-DOTATATE) is the gold standard imaging modality for well-differentiated neuroendocrine tumors (NETs), whereas 68Ga-PSMA PET/CT is routinely used in prostate cancer. PSMA PET can incidentally localize to other malignancies due to PSMA expression in the tumor neovasculature, but its role in NETs is still unclear.

Case presentation: We present the case of a 40-year-old male with metastatic ileal NET (midgut carcinoid) who had undergone 68Ga-DOTATATE and 68Ga-PSMA PET/CT imaging. DOTATATE PET/CT showed intense radiotracer uptake in the primary ileal tumor and multiple liver metastases (SUVmax ~15), confirming strong somatostatin receptor expression. In striking contrast, PSMA PET/CT demonstrated no abnormal uptake in any of the lesions. The patient had no history of prostate cancer.

Discussion: This case illustrates the rare discordance between DOTATATE and PSMA tracer uptake in NET. Prior literature reports PSMA-avid disease in some NETs (especially pancreatic NETs), which is attributed to PSMA expression in tumor-associated neovasculature. Our midgut NET case showed an absence of PSMA uptake, suggesting heterogeneity in PSMA expression across NET subtypes and tumor microenvironments.

Conclusion: 68Ga-PSMA PET can be negative in DOTATATE-positive midgut NETs, underscoring the importance of somatostatin receptor imaging for disease evaluation and caution against assumptions of universal PSMA avidity in NETs.