Abstract Disclosure: A.T. Wahba: None. J.S. Dillon: Advisory Board Member; Self; Crinetics Pharmaceuticals, CA. A 76-year-old woman presented to the Neuroendocrine Tumor (NET) Clinic for evaluation of sore mouth, perianal area and itchy ankles. She had a medical history notable for glucagonoma, status post distal pancreatectomy and splenectomy in 1988, 32 years prior to her current presentation. She recalled that she had CT imaging post operatively for a few years, but no more recent imaging. She was diagnosed with diabetes mellitus in approximately 2002, with highly variable glucose control. She developed a left leg DVT with pulmonary emboli one year prior to presentation. Shortly after her thromboembolic events, she noted her current presenting complaints. A CT abdomen scan with contrast was reported as normal. Three months later, an abdomen ultrasound for evaluation of right upper quadrant pain and intractable vomiting, showed a liver mass. MRI revealed a contrast enhancing 3.1x2.1x1.8 cm lesion in liver segment 6 and 7. Her plasma Glucagon concentration, which had been undetectable when last checked in 2007, was 382 (N: < 80 pg/ml). CT-guided needle biopsy of the liver lesion confirmed a well differentiated neuroendocrine tumor, immunohistochemically positive for somatostatin receptor 2 (SSTR2A), Islet-1 and PAX6, with low mitotic count and Ki-67 proliferation index of 0.45%. Gallium-68 DOTATATE-PET scan showed a single avid hepatic metastasis, with no other evidence of somatostatin receptor expressing tumor. She was initially started on a combination of short-acting Octreotide 100 mcg TID and monthly 20 mg Sandostatin LAR injections for symptomatic relief. Zinc copper 100 mg capsules were prescribed with significant improvement of skin rash and glossitis within 2-4 months. Repeat MRI abdomen at 3 months and 6 months showed a stable single liver lesion without evidence of additional metastasis. She has continued annual clinic visits and abdomen MRI follow up with stable imaging findings at 3 years. Percutaneous ablation, trans hepatic arterial embolization and surgical resection were discussed, but the patient preferred a more conservative approach of monthly octreotide LAR, which she tolerated well, and which resolved her symptoms. Glucagonoma syndrome presents classically with 5D’s: Dermatitis (Necrolytic Migratory Erythema), DVTs, Diabetes mellitus, Depression, Diarrhea. The National Comprehensive Cancer Network guidelines recommend monitoring glucagonoma patients post-resection for up to 10 years with clinical evaluation, glucagon levels every 6-12 months and imaging studies as clinically indicated. Our case illustrates that recurrence can occur after 30 years from initial resection and that longer surveillance should be considered. Presentation: 6/3/2024