C31Malignant neoplasm of accessory sinuses
Code usage status
Primary diagnosis
Select a more specific code
Apply only when it matches the confirmed diagnosis and the documented clinical record.
Specificity
Do not use C31 directly
Use the most specific code supported by the record.
- Chapter II
- Neoplasms
- Group C00-C97
- Malignant neoplasms U ác tính
- Official Vietnamese name
- U ác tính ở xoang phụ
Related C31 codes
C31.0
Primary diagnosis candidate
Maxillary sinus
C31.1
Primary diagnosis candidate
Ethmoidal sinus
C31.2
Primary diagnosis candidate
Frontal sinus
C31.3
Primary diagnosis candidate
Sphenoidal sinus
C31.8
Primary diagnosis candidate
Overlapping lesion of accessory sinuses
C31.9
Primary diagnosis candidate
Accessory sinus, unspecified
Clinical record checklist
View coding guide →- Confirm that the code matches the final documented diagnosis.
- Use one primary-diagnosis code and record only relevant additional conditions.
- Review Ministry indicators, inclusions, exclusions and notes.
- Do not infer a diagnosis beyond the clinical record.
2026 regulatory basis
Indicators are taken from columns 24–29 of the classification accompanying Circular 06/2026/TT-BYT, cross-referenced with Decision 1849/QĐ-BYT and Official Dispatch 4059/BYT-BH.
