Immune checkpoint inhibitor associated bullous pemphigoid: A single-centre retrospective study

lichenoid reactions often present atypically, reflecting the diverse clinical patterns of immune dysregulation and are thought to result from enhanced activity of Th1 and Th17 effector T-cells.Lichen planus (LP) typically affects flexural and dorsal surfaces of the upper limbs, shins, and the lower back, with frequent oral mucosal involvement.Our case is notable for its atypical umbilical presentation.While Koebner phenomenon was considered, it was deemed unlikely as other scars remained unaffected.The PD-1 signalling pathway modulates cytokine production, including IFN, IL-2, IL-17, and TNF-, which are key mediators of immune dysregulation in LP and psoriasis, suggesting potential mechanistic overlap.Umbilical involvement in lichen planus is exceedingly rare, with only three cases reported in the literature, including one instance of nivolumab-induced umbilical LP [2].We describe a second case of checkpoint-inhibitor-induced umbilical LP, adding to the limited but growing evidence of this uncommon manifestation.Checkpoint-inhibitor therapy has revolutionized cancer treatment, but its immune-related side effects require timely recognition and management to prevent severe outcomes.Increasing reports of atypical lichenoid reactions highlight the spectrum of these events.Our report adds evidence of umbilical/psoriasiform LP as a distinct clinical pattern, highlighting the importance of awareness among oncologists and dermatologists.