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

## TL;DR

This paper presents a case of a rare and aggressive lymphoma that can mimic common inflammatory conditions, emphasizing the need for early diagnosis and awareness.

## Contribution

The novelty lies in highlighting the diagnostic challenges and clinical presentation of extranodal NK/T-cell lymphoma through a detailed case report.

## Key findings

- The patient's symptoms initially mimicked chronic sinusitis or dacryocystitis but were later confirmed as extranodal NK/T-cell lymphoma.
- Histopathological and immunohistochemical analysis confirmed the presence of EBV-associated lymphoma with specific markers like CD2, CD56, and EBER.
- The case underscores the poor prognosis and aggressive nature of this lymphoma despite standard treatment approaches.

## Abstract

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.