Mid-treatment Axillary Lymph Node Metastasis of Undifferentiated Nasopharyngeal Carcinoma: An Unprecedented Case.

Nasopharyngeal carcinoma (NPC) usually spreads through the retropharyngeal and cervical lymph nodes, whereas axillary involvement is exceptionally rare and represents non-regional nodal disease. We report a 55-year-old man with cT2N3M0 undifferentiated non-keratinizing NPC (UCNT) who received induction gemcitabine-cisplatin chemotherapy followed by definitive concurrent chemoradiotherapy. After six radiotherapy fractions, the patient developed left axillary pain. Ultrasonography revealed ipsilateral axillary lymphadenopathy, and excisional biopsy demonstrated a poorly differentiated carcinoma morphologically compatible with the known nasopharyngeal primary. Following multidisciplinary review, concurrent chemoradiotherapy was completed as planned, and the patient was referred for consideration of systemic treatment. This case highlights the importance of promptly investigating newly developed axillary lymphadenopathy during treatment and obtaining histopathological confirmation to guide multidisciplinary management.