False-positive finding of retropharyngeal lymph node recurrence in both fluorine (18)FDG PET and MRI in a patient with nasopharyngeal carcinoma.

BACKGROUND: Biopsy of the retropharyngeal node is not routinely accessible. The diagnosis of retropharyngeal lymph node recurrence in patients with nasopharyngeal carcinoma (NPC) is often based on an imaging study. METHODS: We reported a patient with NPC who was incorrectly diagnosed with left retropharyngeal lymph node recurrence by both MRI and positron emission tomography (PET)/CT. RESULTS: A woman who was treated for stage IVA NPC 2 years previously was found to have a nodal lesion in the left retropharyngeal space on MRI together with focal fluorodeoxyglucose (FDG) uptake on PET/CT. Locoregional recurrence was suspected, and surgery was performed. Subsequent pathology results showed reactive lymphoid hyperplasia. CONCLUSION: Although tissue biopsy for the retropharyngeal node is technically difficult, this case demonstrates that tumor recurrence cannot be diagnosed even based on both positive findings on MRI and PET/CT in patients with NPC.