Composite Inflammatory Indices for the Differentiation of Tuberculosis, Sarcoidosis, and Reactive Lymphadenopathy in...

Differentiating mediastinal lymphadenopathy (LAP) due to tuberculosis, sarcoidosis, and reactive causes remains challenging because of overlapping clinical and radiological features. This study aimed to evaluate the diagnostic value of the systemic inflammation composite index (SICI), the platelet inflammation composite index (PICI), and other hematological indices for this differentiation.

This retrospective study included 223 patients who underwent endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) for mediastinal LAP between 2020 and 2025. Pre-procedural laboratory data were used to calculate the platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), and the newly defined SICI and PICI.

PLR, NLR, SII, SICI, and PICI levels were highest in the tuberculosis group and were significantly higher in patients with granulomatous LAP than in those with reactive LAP (p < 0.001 for all). In differentiating tuberculosis from sarcoidosis, a SICI cut-off value of 10966.6 yielded a sensitivity of 83% and a specificity of 63%, while a PICI cut-off value of 2.2 yielded a sensitivity of 85% and a specificity of 60%. For distinguishing granulomatous from reactive LAP, the optimal cut-off values were 77.4 for PLR (sensitivity 98%, specificity 67%), 2721.5 for SICI (sensitivity 89%, specificity 63%), and 0.69 for PICI (sensitivity 87%, specificity 61%).

SICI and PICI, introduced for the first time in the literature, are readily available composite indices that may aid in differentiating tuberculosis-, sarcoidosis-, and reactive LAP-related mediastinal LAP.