Fig 4.

Axial T2-weighted MR image through the neck in a 45-year-old man presenting with neck masses. The enlarged solid left level 2A node measured 3.5 cm in maximal diameter with additional abnormal nodes seen on the right at 2A and bilaterally at levels 3 and 5A. No primary tumor was evident on clinical examination or on this MR imaging. In the absence of a primary tumor, it is difficult to determine which nodal table to use, though most unknown primary tumors are HPV/p16(+) OPSCC. If fine-needle aspiration of the node reveals HPV/p16(+), then an OPSCC primary would be assumed and this would be assigned T0N2. If pathology revealed HPV-negative, p16 negative, and ENB negative, then this would be assigned N2c and no primary site assigned. Fine-needle aspiration revealed this to be undifferentiated, nonkeratinizing carcinoma EBV+, with categories then assigned as T0N2 NPC.