Neuroendocrine tumors (NET) are abnormal growths that occur anywhere in the body, making diagnosis challenging. NETs can be benign (non-cancerous) or malignant (cancerous) and most often occur in body sites such as the small intestine, appendix, rectum, lungs, and pancreas.
The three most common NET types include:
- Carcinoid tumors: Typically occurring in the digestive tract, lungs, appendix, or thymus.
- Pancreatic neuroendocrine tumors: Occurring in and outside of the pancreas, also called islet cell tumors.
- Pheochromocytoma: A rare type of NET, most commonly developing in the adrenal gland.
Tumor Code Assignment
To assign a neuroendocrine tumor code, first look in the alphabetic index under tumor rather than going to the neoplasm table. Under tumor, NETs are cross-indexed under carcinoid, neuroendocrine, or islet cell.
Next, go to Chapter 2: Neoplasms (C00-D49), where you’ll find malignant neuroendocrine tumors under category C7A.- and C7B.- (secondary neuroendocrine tumors). Code benign neuroendocrine tumors to D3A.-.
Tip: If you are having difficulty locating the code in the tabular list, go to the start of the chapter and review the blocks of codes to determine the placement in the chapter. C7A.- & C&B codes are found after code C75.- and before code C76.- while D3A.- codes are found after D36.- and before D37.-.
Tumor code structure ranges from four to six characters depending on the specificity of the location.
Malignancy Code Assignment
An instructional note under category C7A.- states, “code also any associated multiple endocrine neoplasia [MEN] syndromes (E21.2-)”.
Multiple endocrine neoplasia is a grouping of disorders that affect the body’s network of hormone-producing glands caused by mutations in genes that regulate cell growth.
MEN Type 1 (E31.21) frequently involves tumors of the parathyroid glands, the pituitary gland, and the pancreas. MEN Type 2 has type A (E31.22) and type B (E31.23), and the most common type is a triad of medullary thyroid carcinoma, adrenal gland tumor, and parathyroid hyperplasia.
Another instructional note under C7A.- states to “use additional code to identify any associated endocrine syndrome such as carcinoid syndrome (E34.0).” Carcinoid syndrome is characteristic of neuroendocrine tumors of the midgut that metastasize to the liver.
C7B.- (secondary neuroendocrine tumors) includes secondary metastases, which are considered active carcinoid tumors and have an instructional note, “use additional code to identify functional activity.”
All neoplasms are classified in Chapter 2, whether or not they are functional. An additional code from Chapter 4: Endocrine, Nutritional & Metabolic Diseases may be used to identify functional activity associated with neoplasms.
Sites for secondary NETs include carcinoid tumors of the lymph nodes, liver, bone, peritoneum, and Merkel cell carcinoma.
When coding history of malignant carcinoid tumor, utilize the correct Z85.- (personal history of malignant neoplasm) code of the specific location. For example, assign Z85.020 for a history of malignant carcinoid tumor of the stomach.