Background and objectives: The clinical and radiological detection of persistent or recurrent cervical metastasis is difficult in the early phase after surgery and/or radiotherapy. Computed tomograpy (CT) is used in the detection of nodal tumor recurrence, evaluating the underlying soft tissues and bony structures, which cannot be visualized on physical examination. Interpretation of the post-treatment neck can be difficult, with the appearances of complications sometimes mimicking regional metastasis. Because the identification of lymph node central necrosis with imaging is a reliable sign of metastatic lymph node with extracapsular spread, this presentation documents the common clinical and CT findings of necrotic metastatic cervical nodes from head and neck cancer and their differential diagnosis.
Case report: A 40-year-old man with the diagnosis of left parotid ductal adenocarcinoma (T4a N2b M0) underwent left radical parotidectomy with sacrifice of the facial nerve and primary reconstruction, left cervical dissection and postoperative radiotherapy. On the third postoperative day, the neck drain showed a thoracid duct fistula which was successfully managed by conservative treatment. Post radiotherapy CT scan showed a necrotic nodular 1.6–2.4 cm inferior left yugular nodule. Given this finding, he was brought to the operation room for surgical extirpation.
Results: Pathohistologic analysis confirmed the presence of a thoracic duct cyst.
Conclusions: The best radiological predictor of lymph node metastasis is a finding of central lymph node necrosis. The differential diagnosis of central node necrosis in the post-treatment neck with postoperative thoracid duct fistula includes thoracic duct cyst.