Pediatric Synchronous Nasopharyngeal Carcinoma Mimicking Refractory Hodgkin Lymphoma.

A 12-year-old girl with a 5-month history of painless left neck swelling was diagnosed with nodular sclerosis classic Hodgkin lymphoma, stage II, on baseline histopathology and F-18 FDG PET-CT, respectively. Interim PET-CT showed partial metabolic response (Deauville 4); however, end-of-treatment PET-CT revealed increased uptake in the nasopharynx, left parapharyngeal, and submandibular lymph nodes (Deauville 5). A repeat biopsy showed undifferentiated nasopharyngeal carcinoma (NPC). As NPC is a rare malignancy in the pediatric population, additional stains were also performed on the baseline specimen, which confirmed metastatic NPC coexisting with CHL. The patient was then started on cisplatin-based chemoradiation.