ICD-10 Code C11.1 – Malignant neoplasm of posterior wall of nasopharynx (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C11.1 – Malignant neoplasm of posterior wall of nasopharynx
What it is
C11.1 identifies a malignant tumor arising in the posterior wall of the nasopharynx. Use it when documentation specifies this exact anatomic site and confirms cancer.
Clinical signs
Clinical features may include nasal obstruction, epistaxis, ear symptoms from Eustachian tube blockage, or a neck mass. Clinical features vary; refer to documentation.
When to use this code
Use C11.1 when the provider documents a primary malignancy in the posterior wall of the nasopharynx. It is appropriate for confirmed cases, including pathology, imaging, or specialist notes that identify this site. If the record only says nasopharyngeal cancer without location, check documentation.
Do not use for
Do not use this code for benign nasopharyngeal lesions, metastatic disease to the nasopharynx, or cancers documented in a different nasopharyngeal subsite. Check documentation.
Coding tip
Capture the exact anatomic site from the pathology or oncology note before assigning C11.1.