Elevated neutrophil to lymphocyte ratio as an indicator of secondary erythema nodosum, a retrospective observational study

Abstract

Background/aim: Erythema nodosum (EN) is an inflammatory disorder of subcutaneous tissue. Although etiopathogenesis of thedisease is unknown, many predisposing factors such as infections, systemic disease, and drugs have been identified. Neutrophil tolymphocyte ratio (NLR) has been shown to be a novel inflammatory marker in many dermatological diseases. The aim of our study isto investigate NLR in EN patients and evaluate its relation to the underlying cause of the disease.Materials and methods: Between 2014 and 2018, clinical and laboratory data of 395 patients diagnosed with EN and 395 controls wereextracted from patient files. EN patients were grouped as idiopathic EN and secondary EN (EN with an identified underlying cause).Clinical and laboratory characteristics of the two groups were compared.Results: NLR was elevated in EN patients compared to controls (median of 2.38 vs. 1.55, P 2.11), RDW-CV (> 13.65), and CRP (> 5.5)were identified as risk factors for secondary EN (relative risks were 17.16, 2.69, and 2, respectively).Conclusion: Elevated NLR (> 2.11) may be used as a parameter to discriminate secondary EN from idiopathic EN.