Question: Codify Member Answer: Although most neuroendocrine tumors are found in the 209.xx (Neuroendocrine tumor) range, ICD-9 excludes "pancreatic islet cell tumors (157.4)" from that range. The ICD-9 index also will direct you to 157.4 for specific PNETs. For example, if you search "gastrinoma, malignant, pancreas," you'll be pointed to 157.4. Similarly, "tumor, islet cell, malignant, pancreas" points to 157.4. Tip: