ICD-10 Code C31.0 – Malignant neoplasm of maxillary sinus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C31.0 – Malignant neoplasm of maxillary sinus
What it is
C31.0 identifies a malignant tumor arising in the maxillary sinus, one of the paranasal sinuses in the cheek area. Use it when documentation states primary cancer of the maxillary sinus.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include facial pain or pressure, nasal obstruction, epistaxis, swelling, or dental symptoms, but these are not required for coding.
When to use this code
Use C31.0 when the provider documents primary malignant neoplasm of the maxillary sinus, including carcinoma or other malignant histology in that site. It also applies when the record clearly identifies the maxillary sinus as the primary location. Check documentation if laterality, extension, or metastatic disease is the only information available.
Do not use for
Do not use this code for benign sinus tumors, inflammatory sinus disease, or unspecified nasal cavity cancers. If the documentation names another sinus or site, code that location instead.
Coding tip
Verify the exact anatomic site in the pathology or provider note before assigning C31.0.