I just had two of these nearly exact same cases (single 1-4 cm level II node). Both patients had the full work up, pan endoscopy, bilateral tonsillectomies, targeted biopsies (NP, BOT), PET CT, and even MRI. No primary ever found. One patient had p16 positive node, the other was negative. I understand if people only treat ipsilateral sites, especially in the era of PET and MRI, but I was always trained to treat comprehensively (but sparing glottic larynx, per UF and per the Head/Neck chapter in Gunderson written by the UF folks).
Patient 1:
A single node positive ~1.5 cm after a selective neck dissection. HPV positive, no other positive nodes out of like 15 taken. No ECE. I pushed for close observation (he was a very reliable patient) but he was adamantly apposed. One of these "I want to be very aggressive types." We went over NCCN guidelines in this scenario showing option of observe vs. RT. Though his PET and BOT biopsies were positive, his node was HPV/p16 positive and his left base of tongue was suspiciously full on my exam. So I'm treated NPX and OPX down to vallecula, L level Ib through SCLV, and right level II through IV starting elective coverage on the R at the bottom of C1 to spare some parotid. Undissected neck/elective regions to 50 Gy, 10 Gy boost to level II-IV on the L (dissected). No concurrent chemo.
Patient 2:
A 3.5 cm left level IIb node, radiographically possible ECE, p16 and EBV negative. No neck dissection. PET negative other than the one lymph node; tonsillectomy and BOT/NP biopsies negative, scope exam negative. I treated NPX, OPX, contralateral II-IV, ispilateral IB through SCLV to 56 Gy @ 1.6 Gy and the node plus ~1 cm to 70 Gy @ 2.0 Gy/fraction (SIB). She also had concurrent Cis. Didn't go great, required a ~1.5 week treatment break due to confluent mucositis and some confusion on her morphine. Break and pain meds switched to something different and she completed without complication.
