Extranodal natural killer/T-cell lymphoma nasal type: detection by computed tomography features.

OBJECTIVES/HYPOTHESIS Nasal natural killer/T-cell lymphoma (NKTL) often has an infiltrative pattern in computed tomography that makes them difficult to distinguish from benign inflammatory diseases. This study aimed to design a method of measuring the thickness of the nasal floor and nasal septum, determine the critical value of mucosal thickness that may implicate these NKTL cases from benign inflammatory disease, and finally make a complete flowchart to detect NKTL with minimal mistake. STUDY DESIGN Thirty-two patients with nasal NKTL and 173 patients with severe chronic rhinosinusitis with or without polyposis were enrolled. The patients' data were collected retrospectively. METHODS All patients underwent standard computed tomography of the paranasal sinuses. The coronal section near the vertical part of the ground lamina was chosen for measurement, and the thickest points along the nasal floor and septum were measured. RESULTS Patients with NKTL had thicker nasal floors and/or septa than those with chronic rhinosinusitis, recurrent sinusitis, or pansinusitis (P < .001). If the cutoff points of the nasal floor and nasal septum thickness were set at 2.0 mm and 2.5 mm, respectively, the probability of being thicker than the corresponding points in the CRS group was <2%, and the possibility of other diagnoses should be considered. CONCLUSIONS Nasal floor mucosal thickness >2.0 mm or nasal septum mucosal thickness >2.5 mm may be indicators serving as one of several important hints for implicit NKTL. Finally, we established a diagnostic flowchart to include all of these important hints. LEVEL OF EVIDENCE 4.