ICD-10 Code C31.2 – Malignant neoplasm of frontal sinus (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C31.2 – Malignant neoplasm of frontal sinus
What it is
C31.2 identifies a malignant tumor arising in the frontal sinus, one of the air-filled cavities above the eyes. Use it when documentation specifies primary cancer of the frontal sinus.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings may include facial pressure, nasal obstruction, swelling, or symptoms from local invasion, but you should code only what is documented.
When to use this code
Use this code when the provider documents a primary malignant neoplasm of the frontal sinus, whether newly diagnosed or under active evaluation. It also applies when pathology, imaging, or operative notes clearly identify the frontal sinus as the primary site. If the site is uncertain, check documentation.
Do not use for
Do not use C31.2 for benign frontal sinus lesions, inflammatory sinus disease, or metastatic tumors to the frontal sinus. If the record does not confirm a malignant primary site, check documentation.
Coding tip
Verify the exact sinus site in the pathology or operative report before assigning C31.2.