Evaluation of new inflammatory biomarkers in serum in patients with simple bone cyst

Objective: In this study, our aim was to measure the serum levels of newly discovered biomarkers, namely presepsin, irisin, and apelin, in patients diagnosed with simple bone cyst and to investigate their association with the characteristics of simple bone cyst. Materials-Methods: This study is a level III prospective, analytical clinical study. Patients diagnosed with simple bone cyst and admitted to the Department of Orthopedics and Traumatology, Faculty of Medicine, Dicle University, between March 1, 2021, and November 1, 2022, were included in the study. Patients with radiological imaging and clinical findings consistent with a simple bone cyst lesion or those who underwent biopsy were included. A total of 30 patients (group 1) and 30 healthy individuals (group 2) were included in the study. Apelin, Irisin, and Presepsin levels in serum from the patient and control groups were measured using the ELISA method. The obtained values and demographic data of the patients, including tumor location, presence of pathological fracture, cyst index, type of treatment performed, follow-up period, final healing status, and postoperative recurrence status, were analyzed. Results: A total of 60 patients were included in our study. The mean age of the patient group was 16,5 ± 11,2 (median: 12, IQR: 8-24,5), while the mean age of the control group was 16,93 ± 2,89 (median: 16, IQR: 15-20). Out of the patients, 21 (70%) were male and 9 (30%) were female. Of the cysts, 18 were latent and 12 were active. 47% of patients had a pathological fracture at presentation, while 16 did not. The median cyst index was 2.25 (IQR: 1.54-5.38), calculated using the Kaelin and MacEwen method. The presepsin level of the patient group was found to be significantly higher (p=0.013) than the presepsin level of the control group, with values of 747,92 (418,6-1042,9) and 475,5 (228-691,25), respectively. The area under the curve was 0,687, and a cut-off value of 486,33 ng/ml was selected, resulting in a sensitivity of 73,3% and a specificity of 53,3%. The irisin level of the patient group was significantly lower (p=0.013) compared to the control group, with values of 3,4 (2,12-5,5) and 5,2 (3,67-7,65), respectively. ROC analysis was performed, and a cut-off value of 3,56 ng/ml was selected, with a sensitivity of 80%, a specificity of 53%, and an area under the curve of 0,687. There was no significant difference in apelin levels between the patient and control groups (p>0.05). A negative correlation was found between patient age and cyst index (p=0.005). The cyst index was significantly higher in active cysts compared to latent cysts (p=0.008). The frequency of active lesions was higher in patients presenting with a pathological fracture compared to those without a pathological fracture (p=0.001). Patients with active cysts were younger than those with latent cysts, and the difference was statistically significant (p=0.004). The cyst index values of cysts located in the humerus were significantly higher than those located in the femur (p=0.03). Active cysts were found to be more associated with a proximal location compared to a diaphyseal or distal location (p=0.01). The presepsin/neutrophil ratio and apelin/neutrophil ratio were significantly lower in patients with active cysts compared to those with latent cysts, and the differences were statistically significant (p=0.034 and p=0.038, respectively). ROC analysis was performed for these associations. The presepsin/neutrophil ratio and apelin/neutrophil ratio had predictive capabilities for active cysts, with area under the curve values of 0,731 and 0,727, cut-off values of 115,18 ng/ml and 3,02 ng/ml, sensitivities of 94% and 89%, and specificities of 58% and 50%, respectively. The irisin/ALP values were significantly higher in patients with active lesions, with a median of 68,6 (IQR: 39,6-123,5), compared to patients with latent lesions, with a median of 25,6 (IQR: 15,9-72,4) (p=0.034). The area under the curve in the ROC analysis was 0,731, with a cut-off value of 32,1 ng/ml, a sensitivity of 91%, and a specificity of 55%. There was a positive correlation between the neutrophil/CRP ratio and presepsin values in the patient group (p=0.038). Additionally, there were positive correlations between presepsin values and apelin, presepsin values and irisin, as well as apelin values and irisin values in the patient group (p=0.000, p=0.004, and p=0.002, respectively). Conclusion: The pathogenesis of simple bone cysts remains uncertain. Analysis of changing biomarkers in the serum may be helpful in understanding the pathogenesis and monitoring the prognosis. Keywords: Simple bone cyst, Presepsin, Irisin, Apelin