The endogenous Orphanin FQ/Nociceptin ligand concentration expression in the peritoneal fluid of women with peritoneal EM (mean ± SD: 2.81 ± 11.59) and controls (7.88 ± 22.07) was not statistically different (p = 0.586; Figure 3). Here, PNOC is linked to erythema multiforme.