ICD-10 Code E31.23 – Multiple endocrine neoplasia [MEN] type IIB (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E31.23 – Multiple endocrine neoplasia [MEN] type IIB
What it is
E31.23 identifies multiple endocrine neoplasia type IIB, an inherited syndrome that causes tumors or overgrowth in more than one endocrine gland. It is a specific diagnosis, not a symptom code.
Clinical signs
Clinical features vary; refer to documentation. Commonly documented findings include medullary thyroid carcinoma, pheochromocytoma, and mucosal neuromas, with possible marfanoid body habitus.
When to use this code
Use this code when the provider documents MEN type IIB, MEN 2B, or the full syndrome name. It may also apply when the record clearly supports the inherited syndrome, even if one tumor is the main reason for the visit. Check documentation if the note only mentions a single endocrine tumor without naming the syndrome.
Do not use for
Do not use this code for unspecified endocrine neoplasia or for MEN type IIA. If the record does not identify type IIB, check documentation before assigning E31.23.
Coding tip
Code E31.23 only when the syndrome is explicitly documented; capture associated neoplasms separately when they are also reported.