68Ga-DOTATATE PET/CT Distinguishes Neuroendocrine Tumor Mesenteric Lymph Node Metastasis From an Extensive IgG4-Positive Fibrosis Surrounding It.

A 56-year-old woman presented with right iliac fossa pain. Abdominal CT showed a mesenteric mass in the right iliac fossa, adjacent to the vena cava inferior and right ureter. Biopsy of the mass revealed a well-differentiated neuroendocrine tumor. 68Ga-DOTATATE PET/CT showed strong somatostatin receptor expression only within in a small, central area of this mesenteric mass, with faint 68Ga-DOTATATE uptake in the majority of this mesenteric mass. Pathology revealed an IgG4-positive storiform fibrosis surrounding a mesenteric adenopathy. 68Ga-DOTATATE PET/CT discriminates between neuroendocrine tumor lymph node metastases and fibrosis, hereby avoiding potential sampling error of tumor biopsies and guiding surgical approach.