Malignant neoplasm of accessory sinuses (C31) ICD-10-CM
The C31 code range covers malignant neoplasm of accessory sinuses with 7 ICD-10-CM diagnosis codes. 6 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Codes in the C31 Range 7 codes · 6 billable
- C31 Malignant neoplasm of accessory sinusesNon-billable
- C31.0 Malignant neoplasm of maxillary sinus
- C31.1 Malignant neoplasm of ethmoidal sinus
- C31.2 Malignant neoplasm of frontal sinus
- C31.3 Malignant neoplasm of sphenoid sinus
- C31.8 Malignant neoplasm of overlapping sites of accessory sinuses
- C31.9 Malignant neoplasm of accessory sinus, unspecified
About the C31 Code Range
The ICD-10 code C31 series is used to classify malignant tumors found in the accessory sinuses, which are air-filled spaces around the nose. These codes specify cancers located in particular sinuses such as maxillary, ethmoidal, frontal, and sphenoid sinuses, or cases where multiple sites are involved or unspecified.
The ICD-10 code for malignant neoplasm of accessory sinuses includes several detailed subcodes. For example, C31.0 identifies cancers in the maxillary sinus, often referred to by synonyms like adenocarcinoma or squamous cell carcinoma of the maxillary sinus. Similarly, C31.1 covers malignant tumors of the ethmoidal sinus, with terms such as carcinoma of ethmoidal sinus used interchangeably. Codes C31.2 and C31.3 refer to frontal and sphenoid sinus cancers, respectively. When tumors affect multiple accessory sinuses, C31.8 is applied, and C31.9 is used when the exact sinus site is unspecified. Recognizing these synonyms helps medical coders accurately match commonly used cancer names to the precise ICD-10 code, ensuring correct documentation and treatment planning.
Questions About This Page
How many billable codes are in the C31 range?
Of the 7 codes in this range, 6 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the C31 range classify?
The range classifies malignant neoplasm of accessory sinuses. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
