Nasopharyngeal carcinoma masquerading as a primary sinonasal mass: a case report

Background Nasopharyngeal carcinoma (NPC) typically arises from the nasopharyngeal vault and most commonly presents with cervical lymphadenopathy or otologic symptoms. Presentation with a dominant anterior sinonasal mass is exceptionally uncommon and may obscure the true site of origin, leading to diagnostic misclassification as a primary sinonasal malignancy. Cross-sectional imaging, such as computed tomography (CT), may be inconclusive in such cases, necessitating a multimodal approach for accurate diagnosis. Case presentation A 54-year-old Indian male presented with progressive unilateral nasal obstruction, recurrent epistaxis, facial swelling, visual impairment, and bilateral hearing loss. Nasal endoscopy revealed a bulky anterior sinonasal mass obstructing visualization of the nasopharynx. CT imaging showed a destructive mass involving the nasal cavity and paranasal sinuses with posterior extension toward the nasopharynx though the primary site remained uncertain. Incisional biopsy revealed a poorly differentiated non-keratinizing carcinoma. Immunohistochemistry (IHC) for p40/p63 and Epstein–Barr virus (EBV)-encoded RNA in situ hybridization confirmed nasopharyngeal carcinoma. Whole-body 1⁸F-fluorodeoxyglucose (FDG) positron emission tomography–computed tomography (PET-CT) demonstrated a nasopharyngeal primary with extensive loco-regional invasion, bilateral cervical nodes, and skeletal metastases (cT4bN2cM1). The patient received palliative radiotherapy but deteriorated rapidly and died shortly thereafter. Conclusion This case highlights a diagnostic pitfall in which nasopharyngeal carcinoma presents as a predominant anterior sinonasal mass, closely mimicking a primary sinonasal malignancy. Reliance on cross-sectional imaging alone may delay diagnosis. Early biopsy, EBV testing, and multimodal evaluation including PET-CT are essential for accurate tumor localization and staging. Awareness of this atypical presentation may help clinicians avoid diagnostic delay and optimize patient care.