Nasopharyngeal carcinoma (NPC) is staged using AJCC 8th edition. A tumor that involves the parapharyngeal space and extends to the prevertebral musculature, with a single ipsilateral cervical node of 4 cm and no distant metastasis, is classified as:
- A Stage III ✓
- B Stage IVA
- C Stage IVB
- D Stage II
Correct answer: A. Stage III
Explanation
In AJCC 8th edition NPC staging, prevertebral muscle involvement classifies the primary as T4, and a single ipsilateral cervical node up to 6 cm without supraclavicular extension is N1. T4N1M0 = Stage III. Stage IVA is T4N2M0 or any TN3M0. Stage IVB is any T any N M1. Prevertebral muscle involvement was a T4 feature introduced in the 8th edition; in the 7th edition it was also T4, but distinguishing from parapharyngeal alone (T2) is critical for staging.
Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.
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