Pulmonary extranodal NK/T-cell lymphoma: A clinicopathological analysis of five patients.

Objective: Our goal was to investigate the clinicopathological features of extranodal natural killer (NK)/T-cell lymphoma (ENKTL). Material and Methods: A total of five newly identified (5 biopsy samples) untreated cases of pulmonary ENKTL were collected between January 2016 and January 2024. The clinical characteristic pathology features on hematoxylin-eosin-staining sections, immunohistochemistry stating, treatment responses, and prognoses were retrospectively analyzed. Results: Among the five patients, four were male and one was female, and their ages varied between 48 and 63 years. All five patients were initially diagnosed with stage IV disease. Histological examination revealed either scattered or localized clusters of highly pleomorphic tumor lymphocytes associated with necrosis and a significant presence of inflammatory cells. Most tumor cells expressed cluster of differentiation (CD)3, T-cell intracellular antigen-1, and granzyme B, whereas there was an absence of CD20, CD79a, or CD5 expression. The expression of CD56 was detected in four out of the five patients. Only two patients were tested for programmed cell death ligand 1, with one out of two patients exhibiting positivity (Tumor Proportion Score (TPS) 80%). The Ki-67 proliferation index varied from 40% to 90%. All patients tested positive for Epstein- Barr virus-encoded ribonucleic acid (RNA) (EBER) through fluorescence Conclusion: Pulmonary ENKTL is an uncommon, aggressive cancer associated with a bleak prognosis. The likelihood of misdiagnosis is high because of the presence of necrotic lesions and various cell types. Accurate diagnosis relies heavily on immunohistochemistry and EBER FISH. The aim of our study was to facilitate improved diagnosis of pulmonary ENKTL and to identify treatment strategies for affected individuals.