Malignant neoplasm of other accessory sinuses

This code signifies the presence of a cancerous tumor originating in any accessory sinus other than the maxillary, ethmoid, frontal, or sphenoid sinuses. This typically includes less common sites such as the uncinate process or agger nasi cells. The malignancy is primary to these accessory sinus structures.

Apply this code when documentation clearly specifies a primary malignant neoplasm of an accessory sinus not otherwise classified. This is appropriate for diagnoses like carcinoma of the agger nasi cell or an unspecified accessory sinus malignancy. Ensure the physician's notes confirm the primary nature and specific location within an accessory sinus.

• Always seek documentation specifying the exact accessory sinus involved; if a more specific site (e.g., maxillary) is identified, a more precise code should be used.
• Confirm the neoplasm is primary to the accessory sinus and not a metastatic lesion from another site.
• Sequence this code according to the primary diagnosis guidelines, often as the principal diagnosis if it's the reason for the encounter.