A collision tumor of nasopharyngeal carcinoma and primary mantle cell lymphoma in the nasopharynx: A case report and review of the literature

Background: Nasopharyngeal carcinoma (NPC) is more common in men aged 40 to 59 years, and radiotherapy is an effective treatment. Nasopharyngeal lymphoma (NPL) is rare, and the coexistence of mantle cell lymphoma (MCL) and NPC in the nasopharynx is even rarer. No reports to date have described a collision tumor of NPC and MCL occurring within the same nasopharyngeal mass. We herein report the successful treatment of a unique case of synchronous coexistence of NPC and MCL occurring in the nasopharynx of a Chinese man. Case presentation: A 58-year-old man presented with a 5-month history of swallowing discomfort. Biopsy was taken under nasopharyngoscopy and histopathology revealed NPC. Lesions of the nasopharynx, oropharynx and tonsils, and enlargement lymph nodes of parotid gland, retroauricular and cervical regions were found by magnetic resonance imaging (MRI), which may be a synchronous, double primary tumor in which NPC and NPL co-exist. Pathology consultation confirmed that the biopsy specimen of nasopharynx was a collision tumor of NPC and MCL. Positron emission tomography–computed tomography (PET-CT) revealed thickening of the posterior wall of the nasopharynx, and NPC with lymphoma was considered. Enlargement of pharyngeal lymphatic ring and multiple lymph nodes with high metabolism were evaluated as lymphoma infiltration. The patient received two courses of R-CHOP chemotherapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) followed by head and neck radiotherapy. At the time of this writing, he had remained alive without recurrence for 61 months since the initial treatment and was still undergoing follow-up. Conclusions Magnetic resonance imaging helps identify different components of collision tumors. Pathological examination helps to confirm the diagnosis. Histological examination reveals different components and PET-CT can help determine the extent of the lesion. Dose-adjusted chemotherapy combined with radiotherapy may have good therapeutic effects, but additional case studies are needed for confirmation.