Nasopharyngeal carcinoma with inguinal lymph node metastasis: A case report.

Nasopharyngeal carcinoma (NPC) usually metastasizes to cervical lymph nodes, whereas inguinal lymph node metastases (ILNM) are rare, with only a small number of cases reported. ILNs are an uncommon site of secondary involvement, a phenomenon attributed to their unique anatomical and immunological features. The current study reported a case of NPC in which baseline positron emission tomography/CT showed metastasis from the left pharyngeal recess to the left cervical levels II-III. Mildly increased metabolic activity was observed in levels II-III of the right cervical chain, the left supraclavicular area and the bilateral inguinal area, initially interpreted as reactive hyperplasia. The patient was diagnosed with NPC (T2N1M0, stage IIA, 8th edition of the American Joint Committee on Cancer). At 5 months after the completion of induction chemotherapy and concurrent chemoradiotherapy, the bilateral ILNs showed interval enlargement and biopsy confirmed metastatic NPC. The patient was classified as stage IVB based on biopsy results, prompting appropriate treatment for this advanced stage. This rare case underscores the importance of considering ILNM as a possible metastatic site in NPC, requiring clinicians to perform timely evaluations and lymph node biopsies to prevent clinical understaging due to unrecognized occult metastatic disease, particularly during the early stages of diagnosis.