Objective:To investigate the role of multiparameter flow cytometry (MFC) in detecting non-neoplastic abnormal phenotypes, including monoclonal gammopathy of undetermined significance (MGUS), monoclonal B-cell lymphocytosis (MBL), Fcγ receptor Ⅲb (FcγRⅢB), and CD36 deficiencies.Methods:A retrospective and observational study was conducted on a total of 24 864 patients who underwent one-step screening for leukemia/lymphoma at Hebei Yanda Ludaopei Hospital from January 3, 2020, to March 31, 2024. Clinical data and MFC results of the patients were collected. Patients were grouped by age, group of <45 years (11 495 cases), group of 45-<60 years (5 322 cases), group of ≥60 years (7 081 cases) and disease nature, benign group (8 336 cases), malignant group (15 562), and other diseases group (966 cases). The incidence of non-neoplastic abnormal phenotypes was analyzed across groups.Results:The incidence rates of MGUS, MBL, FcγRⅢB, and CD36 deficiencies were 0.072% (18/24 864), 0.511% (127/24 864), 0.221% (55/24 864), and 0.004% (1/24 864), respectively. MBL incidence was lower in the malignant group than in the benign group ( P<0.001), while MGUS incidence was higher in the malignant group than in the benign group ( P=0.034). The incidence rate of MBL among subtypes within the benign group varied significantly ( P<0.001 ), with the highest incidence in patients with pancytopenia at 2.72% (48/1 765). In the malignant group, the incidence of MBL differed significantly across various disease types ( P<0.001), among which MDS/MPN exhibited the highest incidence at 1.95% (3/154) and 1.30% (2/154). Conclusion:Utility of multiparameter flow cytometry method for one-step screening of leukemia and lymphoma shows variety in detecting non-neoplastic abnormal phenotypes, facilitating the identification of diseases.