Value of Platelet-to-Lymphocyte and Monocyte-to-Lymphocyte Ratios in Differentiating Idiopathic Orbital Inflammation From Orbital Infectious Disease.

Purpose: Monocyte-lymphocyte ratio (MLR) and platelet-lymphocyte ratio (PLR) are emerging biomarkers; they have not been widely utilized in orbital disease. This study investigated the role of these ratios in distinguishing orbital inflammation from infection.

Methods: A retrospective review of medical records was conducted to identify adult patients who presented acutely to a single emergency department at an academic medical center and were diagnosed with serologically and biopsy-proven idiopathic orbital inflammation (IOI, n = 9), orbital cellulitis (OC, n = 14), or necrotizing fasciitis (NF, n = 12). MLR and PLR were calculated from the first blood draw on presentation to the emergency department. Statistical analysis was performed via the Mann-Whitney test with a dedicated computerized software package (GraphPad Prism, La Jolla, CA) with p values <0.05 considered statistically significant.

Results: Mean PLRs were 194.90 (SD = 118.01), 304.21 (SD = 341.39), and 203.38 (SD = 196.32) for IOI, NF, and OC, respectively. Mean MLRs were 0.40 (SD = 0.24), 1.74 (SD = 2.41), and 0.75 (SD = 0.40) for IOI, NF, and OC, respectively. MLR was significantly lower in the IOI group compared to the NF group (p = 0.018) and OC group (p = 0.020). Differences in MLR between OC and NF groups were not statistically significant (p = 0.43).

Conclusion: While MLR showed no significant difference between different infectious etiologies, it was significantly higher in infectious processes than in IOI, distinguishing inflammation from infection. MLR could be a valuable addition to the diagnostic toolkit for triaging patients in the emergency department and initiating prompt, focused therapy.