The Elusive Diagnosis: A Case of Extranodal Natural Killer (NK)/T-Cell Lymphoma

Extranodal natural killer (NK)/T-cell lymphoma is a rare malignant tumor, more prevalent in Asia and Latin America, and associated with Epstein-Barr virus infection. Its diagnosis is challenging due to its clinical presentation, which may mimic chronic sinusitis, dacryocystitis, or granulomatous diseases. This lymphoma follows a rapid and aggressive course, with a poor prognosis. We report the case of a 71-year-old man presenting with nasal obstruction, clear rhinorrhea, and facial heaviness. Initially, acute dacryocystitis and periorbital cellulitis were suspected and treated with antibiotics; however, the patient showed a poor response. After multiple consultations and unsuccessful treatments, a biopsy confirmed the diagnosis of extranodal NK/T-cell lymphoma of the nasal type. Histopathological and immunohistochemical analysis revealed an infiltrate of atypical lymphocytes positive for cluster of differentiation 2 (CD2), cluster of differentiation 56 (CD56), T-cell intracellular antigen-1 (TIA-1), and Epstein-Barr virus-encoded RNA (EBER), with prominent tissue necrosis. This case highlights the diagnostic challenges and aggressive clinical course of sinonasal NK/T-cell lymphoma. Its initial presentation can mimic common inflammatory conditions, requiring a high index of suspicion. Standard treatment includes combined chemotherapy and radiotherapy, yet the prognosis remains poor. This report aims to raise awareness of this entity and emphasize the importance of considering it in atypical or treatment-refractory cases of orbital cellulitis, bacterial sinusitis, and other inflammatory conditions.