Malignant neoplasm of ethmoidal sinus

This code signifies a primary cancerous tumor originating within the ethmoidal sinus, one of the paranasal sinuses located between the eyes. This malignancy can affect the bony walls or the mucosal lining of the ethmoid air cells.

Assign this code when documentation clearly states a primary malignant neoplasm of the ethmoidal sinus. This is typically supported by pathology reports confirming malignancy and imaging studies (e.g., CT, MRI) localizing the tumor to the ethmoid sinus.

• Differentiate from secondary or metastatic tumors to the ethmoidal sinus; use appropriate secondary malignancy codes in those instances.
• Ensure the documentation specifies "ethmoidal sinus" and not a more general "nasal cavity" or "paranasal sinus, unspecified."
• Always sequence this code as the primary diagnosis when it is the reason for the encounter, unless specific coding guidelines dictate otherwise (e.g., for complications of treatment).