D13.7

Benign neoplasm of endocrine pancreas

Benign neoplasm of the endocrine pancreas refers to a non-cancerous tumor arising from the hormone-producing cells located within the islets of Langerhans. These tumors are a subset of pancreatic neuroendocrine tumors (PanNETs). While biologically benign—meaning they do not typically metastasize or invade surrounding tissues aggressively—they can be clinically significant if they are 'functioning' tumors. Functioning tumors secrete excessive amounts of hormones such as insulin, gastrin, glucagon, or somatostatin, leading to systemic syndromes. The most common type is the insulinoma. Non-functioning benign endocrine pancreatic tumors may remain asymptomatic for long periods or may be discovered incidentally during imaging for unrelated conditions. Clinical management often involves surgical resection to prevent potential malignant transformation (as some neuroendocrine tumors have uncertain malignant potential) or to resolve severe hormonal imbalances.

Clinical Symptoms

  • Fasting hypoglycemia (sweating, palpitations, tremors, confusion, and syncope)
  • Neuroglycopenic symptoms (visual disturbances, personality changes, seizures)
  • Weight gain (often due to compensatory overeating to avoid hypoglycemia)
  • Recurrent peptic ulcers (associated with gastrinoma/Zollinger-Ellison syndrome)
  • Severe watery diarrhea and hypokalemia (associated with VIPomas)
  • Necrolytic migratory erythema (a characteristic skin rash associated with glucagonomas)
  • Diabetes mellitus or glucose intolerance (associated with glucagonomas or somatostatinomas)
  • Steatorrhea and gallstones (associated with somatostatinomas)
  • Epigastric or abdominal pain from local mass effect
  • Jaundice (rare, occurring if the tumor compresses the common bile duct)

Common Causes

  • Sporadic genetic mutations in pancreatic islet cells
  • Multiple Endocrine Neoplasia type 1 (MEN1) syndrome
  • Von Hippel-Lindau (VHL) syndrome
  • Neurofibromatosis type 1 (NF1)
  • Tuberous Sclerosis Complex (TSC)
  • Inactivation of the MEN1 gene (most common somatic mutation in sporadic cases)
  • Loss of heterozygosity in chromosomes 11, 6, and 22

Documentation & Coding Tips

Distinguish between functional and non-functional status.

Example: The patient presents with a 1.2 cm benign neoplasm of the endocrine pancreas located in the tail. Clinical presentation is consistent with a functional insulinoma, confirmed by a 72-hour fast showing symptomatic hypoglycemia with inappropriately elevated insulin levels (15 microU/mL) and C-peptide. Note: Functional status impacts the complexity of medical decision making for HCC and risk adjustment.

Billing Focus: Documentation must specify if the tumor is functional (secreting hormones) or non-functional, as this dictates the complexity of the diagnostic workup.

Clearly document the anatomical site within the pancreas.

Example: Computed tomography of the abdomen reveals a well-circumscribed, hyperenhancing mass measuring 2.0 cm in the pancreatic head, adjacent to the duodenum. Biopsy confirms a benign neuroendocrine tumor (islet cell tumor). No evidence of vascular invasion or lymphadenopathy is present. Patient is scheduled for enucleation of the lesion.

Billing Focus: Anatomical specificity (head, body, tail) supports the necessity of specific surgical CPT codes (e.g., Whipple vs. distal pancreatectomy).

Explicitly state the benign nature based on histopathology.

Example: Pathology report from endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) identifies a Grade 1 neuroendocrine tumor of the endocrine pancreas with a Ki-67 index of less than 2 percent and fewer than 2 mitoses per 10 high-power fields. The findings are diagnostic of a benign neoplasm (D13.7). Patient currently asymptomatic from a hormonal standpoint.

Billing Focus: Histopathological confirmation of benign status is essential to distinguish D13.7 from C25.4 (malignant) or D37.8 (uncertain behavior).

Link secondary conditions to the primary neoplasm.

Example: Patient with known benign endocrine pancreatic tumor (D13.7) presents with recurrent peptic ulcers refractory to standard PPI therapy. Laboratory tests show fasting gastrin levels over 1000 pg/mL, diagnostic of a gastrinoma. Clinical management involves high-dose acid suppression and surgical consultation for tumor resection.

Billing Focus: Coding must include the benign neoplasm and the specific endocrine manifestation (e.g., E16.4 for gastrinoma or E16.1 for hypoglycemia).

Document the absence of metastatic features to support benign classification.

Example: Surveillance MRI of the abdomen shows a stable 1.5 cm islet cell tumor in the pancreatic body. Thorough review of the liver and regional lymph nodes shows no evidence of metastatic disease or interval growth over 12 months. Tumor remains categorized as a benign neoplasm of the endocrine pancreas.

Billing Focus: Ongoing surveillance notes must justify the use of a benign code vs. a history of malignancy code (Z85.07).

Relevant CPT Codes