C11.1

Billable

Malignant neoplasm of posterior wall of nasopharynx

HCC Category Mapping

V28HCC 21 — Breast, Prostate, Colorectal and Other Cancers and Tumors

0.545

V24HCC 11 — Colorectal, Bladder, and Other Cancers

0.306

ESRDHCC 11 — Colorectal, Bladder, and Other Cancers

0.000

What This Code Means

Cancer that starts in the back wall of the nasopharynx, which is the upper part of the throat behind the nose.

Coding Tips

•Verify the specific anatomical location is documented as posterior wall to distinguish from other nasopharyngeal sites
•This location is common in patients with history of Epstein-Barr virus infection or tobacco/alcohol use

Clinical Significance

Malignant neoplasm of the posterior wall of the nasopharynx is the most common site for nasopharyngeal carcinoma, a cancer with unique epidemiology concentrated in Southern China, Southeast Asia, and North Africa. EBV is a key etiologic factor, and plasma EBV DNA is used for monitoring treatment response and detecting recurrence.

Documentation Requirements

✓Pathology-confirmed malignancy with WHO classification (Type I, II, or III)
✓EBV status including plasma EBV DNA levels
✓Documentation specifying posterior wall of nasopharynx
✓MRI of nasopharynx and skull base for staging
✓Assessment of cranial nerve involvement (particularly CN V and VI)

Commonly Confused Codes

C11.0 — Superior wall of nasopharynx; the posterior wall is the back surface, distinct from the roof C11.2 — Lateral wall of nasopharynx; the posterior wall is midline, the lateral walls are on the sides C10.3 — Posterior wall of oropharynx; ensure the tumor is in the nasopharynx (behind nose) not oropharynx (behind mouth)C11.9 — Nasopharynx, unspecified; avoid when posterior wall is documented

Code Hierarchy

└C11Malignant neoplasm of nasopharynx └C11.1Malignant neoplasm of posterior wall of nasopharynx

└C11.1Malignant neoplasm of posterior wall of nasopharynx