Large Granular Lymphocytes and Large Granular Lymphocytic Leukemia: A Real-World Case-Control Study

Objective: This study aimed to compare differences in peripheral blood large granular lymphocytes (LGLs) between healthy donors and patients with large granular lymphocyte leukemia (LGLL), and explore methods to boost the sensitivity of peripheral blood smear examination for LGLL identification. Materials and Methods: We retrospectively analyzed 391 healthy donors and 53 LGLL patients from 2023 to 2024. Results: Results showed significant differences in LGL proportion, absolute count and its proportion in lymphocytes between the two groups (all P<0.001). There was no significant difference between smear and flow cytometric results. ROC curve analysis determined 24% LGL proportion as the cutoff value. Conclusion: Peripheral blood smear can be used for initial LGLL screening, and the thresholds of 0.5×10⁹/L LGL absolute count and 24% LGL proportion effectively screen LGLL patients.