Endocrine Tumors of Pancreas

PNETs Overview - Pancreatic Powerhouses

• Pancreatic Neuroendocrine Tumors (PNETs): Originate from pancreatic islet cells.
• WHO 2019/2022 Classification & Grading:
  • Well-differentiated PNET (morphology preserved):
    • G1: Mitoses <2/10 HPF AND Ki-67 <3%
    • G2: Mitoses 2-20/10 HPF OR Ki-67 3-20%
    • G3: Mitoses >20/10 HPF OR Ki-67 >20%
  • Poorly-differentiated Neuroendocrine Carcinoma (NEC G3): High grade, poor morphology, Ki-67 often >55%.
  • MiNEN (Mixed Neuroendocrine-Non-neuroendocrine Neoplasm).
• Functional (hormone-secreting, e.g., Insulinoma, Gastrinoma) vs. Non-functional (more common, present with mass effects).

⭐ Most PNETs are well-differentiated tumors (G1/G2), but Ki-67 index and mitotic count are crucial for grading and prognosis.

Functional PNETs: Insulinoma & Gastrinoma - Sweet & Sour Syndromes

• Insulinoma ("Sweet")

  • Most common PNET; β-cell origin; secretes insulin → hypoglycemia.
  • Whipple's Triad:
    • Hypoglycemic symptoms.
    • Plasma glucose <50 mg/dL.
    • Relief with glucose.
  • Dx: ↑Insulin, ↑C-peptide with hypoglycemia (72-hr fast).
  • ~90% benign, solitary. Tx: Surgery.

• Gastrinoma ("Sour") - Zollinger-Ellison Syndrome (ZES)

  • G-cell origin (pancreas/duodenum); secretes gastrin → ↑HCl.
  • Clinical: Refractory/multiple peptic ulcers (PUDs), diarrhea.
  • Dx:
    • ↑Fasting gastrin (>1000 pg/mL with gastric pH <2).
    • Positive Secretin stimulation test (paradoxical ↑gastrin).
  • ~25% MEN1 associated. >60% malignant.
  • Tx: PPIs, surgery.

⭐ Insulinomas are typically benign (~90%) and solitary, presenting with Whipple's triad, while gastrinomas (ZES) are often malignant, multiple, and associated with MEN1.

Other Functional PNETs - Rare Hormone Havoc

• Glucagonoma:
  • Presents with syndrome: Diabetes, Dermatitis (necrolytic migratory erythema), DVT, Depression (📌 4Ds).
  • ↑ Glucagon. Often in pancreatic tail. High malignant potential.

  ⭐ Glucagonoma syndrome classically presents with the '4Ds': Dermatitis (necrolytic migratory erythema), Diabetes, DVT, and Depression.

• VIPoma (Verner-Morrison Syndrome):
  • Causes WDHA syndrome: Watery Diarrhea, Hypokalemia, Achlorhydria ("Pancreatic Cholera").
  • ↑ VIP. Often in pancreatic tail. ~50% malignant.

  ⭐ VIPomas cause WDHA syndrome (Watery Diarrhea, Hypokalemia, Achlorhydria).

• Somatostatinoma:
  • Syndrome: Diabetes mellitus, cholelithiasis, steatorrhea, hypochlorhydria.
  • ↑ Somatostatin. Often duodenal or pancreatic. Psammoma bodies common.
• PPoma (Pancreatic Polypeptide-oma):
  • Often clinically silent or presents with vague symptoms. ↑ Pancreatic Polypeptide.

PNETs: Diagnosis & Management - Spotting & Stopping

• Diagnosis

  • Clinical Suspicion: Symptoms (hormonal/mass) or incidental finding.
  • Biochemical Markers:
    • Specific hormone assays.
    • General: Chromogranin A (CgA), Synaptophysin (IHC markers).
  • Imaging:
    • CT/MRI (initial).
    • EUS-FNA (biopsy).
    • Functional: Ga-68 DOTATATE PET/CT (best for staging/localization) or Octreoscan.

  ⭐ Chromogranin A and Synaptophysin are key immunohistochemical markers for PNETs. Somatostatin receptor scintigraphy (Octreoscan) or Ga-68 DOTATATE PET/CT are crucial for localization and staging.

• Management

  • Surgery: Primary treatment for localized PNETs; curative intent.
  • Medical Management (for unresectable/metastatic disease):
    • SSAs (Octreotide, Lanreotide): Control symptoms, inhibit growth.
    • Targeted Therapy: Everolimus (mTORi), Sunitinib (TKI).
    • PRRT: Lu-177 DOTATATE for SSTR-positive tumors.
    • Chemotherapy (e.g., Streptozocin, Temozolomide): Poorly differentiated/high-grade.

High‑Yield Points - ⚡ Biggest Takeaways

• Insulinoma: Most common PNET, causes hypoglycemia (Whipple's triad); often benign.
• Gastrinoma (ZES): Leads to multiple, refractory peptic ulcers; strong MEN 1 association.
• Glucagonoma: Presents with necrolytic migratory erythema, diabetes, DVT, depression (4Ds).
• VIPoma: Characterized by WDHA syndrome (Watery Diarrhea, Hypokalemia, Achlorhydria).
• Somatostatinoma: Causes inhibitory effects: diabetes, cholelithiasis, steatorrhea, hypochlorhydria.
• MEN 1 syndrome is frequently linked with gastrinomas, insulinomas, and glucagonomas.
• Chromogranin A & Synaptophysin are key immunohistochemical markers for PNETs.