A Clinical Study of 66 Cases of Sinonasal Malignant Lymphoma: Results of a Single‐Institution Study

Objective Early diagnosis and treatment of sinonasal malignant lymphoma are crucial because of its diverse clinical and imaging findings and poor prognosis associated with certain histological subtypes. However, the markers that predict the diagnosis and prognosis according to the histological subtypes are unclear. This study aimed to identify these markers. Methods We retrospectively analyzed 66 malignant lymphomas diagnosed using biopsy specimens obtained from the nasal cavity and sinus and treated at our institution. Age, sex, main symptom, primary site, disease stage, histopathological type, blood test parameters, follow‐up period, treatment details, and prognosis were analyzed. Overall survival was defined as the time from diagnosis to death from any cause. Progression‐free survival was defined as the time from diagnosis to disease progression, relapse, or death. Survival curves were estimated using the Kaplan–Meier method and compared using the log‐rank test. Results Diffuse large B‐cell lymphoma (DLBCL) was the most common histological subtype (45 patients), followed by extranodal natural killer (NK)/T‐cell lymphoma (ENKTL; 15 patients). The 5‐year progression‐free survival rates were 50.0% for DLBCL and ENKTL for 28.1%. ENKTL was associated with a significantly poorer prognosis than DLBCL. Among patients with sinonasal DLBCL, CD5‐positivity tended to have a poorer prognosis. Conclusion Sinonasal malignant lymphoma exhibits heterogeneous clinical behavior according to the histological subtype. CD5‐positive sinonasal DLBCL tended to result in worse outcomes. To our knowledge, this is the first study to investigate the prognostic significance of CD5 expression in sinonasal DLBCL. Further studies are needed to clarify its prognostic significance. Level of Evidence 3.