Introduction: The differential diagnosis of sarcoidosis creates a challange due to tuberculosis also having lung and lymph node involvement. Because both diseases show granulomatous inflammation, it may not be possible to distinguish tuberculosis and sarcoidosis in pathological specimens. As a result of the complexity in the differential diagnosis of sarcoidosis and tuberculosis, new markers for differentiation are being investigated.
Objective: The aim of our study is to investigate the value of neutrophil/lymphocyte ratio (NLR) as a possible marker in differentiating sarcoidosis and tuberculosis.
Materials and methods: In our study, 51 acid-fast bacilli (AFB) positive and/or culture-positive patients with pulmonary tuberculosis, 40 patients with biopsy-proven sarcoidosis and a control group consisting of 43 patients were included. In our study, information was collected retrospectively based on hospital records.
Results: Leukocyte and neutrophil counts, NLR, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) were significantly higher, and albumin was significantly lower in the tuberculosis group compared with sarcoidosis (for all parameters P < 0.001). The most appropriate cut-off value of NLR to distinguish tuberculosis from sarcoidosis was determined as 2.55. For this cut-off value of NLR there was 79% sensitivity, 69% specificity, 73% positive predictive value (PPV), 75% negative predictive value (NPV), and area under the curve (AUC) was 0.788. For differentiation of sarcoidosis from tuberculosis, accuracy of the NLR test according to this cut-off value was found as 76%.
Conclusion: NLR as a little known marker in respiratory medicine was found to be supportive in differentiation of tuberculosis and sarcoidosis. More studies on this issue is needed.
Keywords: Granulomatous inflammation; neutrophil-lymphocyte ratio; sarcoidosis; tuberculosis.