Sominidi Damodaran, Sindhuja

Abstract Background Immune checkpoint inhibitors (ICIs) directed against PD-1, PD-L1, and CTLA-4 augment antitumor immune responses but may also induce unintended immune activation, resulting in immune-related adverse events (irAEs). Cutaneous manifestations of irAEs are among the most common, ranging from mild eruptions to severe autoimmune blistering disorders (AIBDs). Although bullous pemphigoid (BP) is the most reported ICI-related autoimmune bullous disorder (irAIBD), data on the spectrum, and management of other ICI-associated AIBDs remain limited. Understanding these reactions is crucial to managing treatment interruptions and influencing oncologic outcomes. Objective This study aims to comprehensively characterize ICI-associated irAIBDs by examining demographics, clinical presentation, disease severity, therapeutic approaches, treatment responses, clinical outcomes, and mortality. Methods A single-institution retrospective chart review was conducted, using a text-based database search from 2011–2023. Adult patients (≥18 years) with biopsy-confirmed AIBDs attributed to ICIs were included. Demographic, oncologic, and immunotherapy details, as well as clinical, histopathologic, and immunofluorescence characteristics of AIBDs, were reviewed. Treatment approaches, outcomes, and mortality data were analyzed. Results Forty-four patients with irAIBDs were identified, predominantly representing males (29, 65.9%) with a mean age of 70.4 years (range: 62-80 years). Lung carcinoma (12, 27.2%) and melanoma (9, 20.4%) were the most frequent underlying malignancies, and pembrolizumab (25, 56.8%) was the most common agent. Bullous pemphigoid (BP) accounted for most cases (36, 81.8%), followed by lichen planus pemphigoides (LPP) (6, 13.6%), with one case each of mucous membrane pemphigoid (MMP) and linear IgA bullous dermatosis (LABD). Pruritus was reported in most (42, 9%) patients, and upper (36, 81.8%), lower (32, 72.2%) extremities and the chest (34, 77.2%) were most often involved. Eosinophilic infiltration was present in most (23, 81.8%) of BP cases, and linear IgG and C3 deposition were the predominant immunofluorescence patterns in BP. Most patients received topical (34, 77.2%) and/or systemic corticosteroids (32, 72.7%), while 16 required at least temporary ICI discontinuation. Four BP (4, 9.1%) patients were treated with dupilumab. Other systemic agents used included doxycycline (22, 50%), intravenous immunoglobulin (IVIG) (5, 11.3%), rituximab (6, 13.6%), dapsone (1, 2.2%), mycophenolate mofetil (1, 2.2%), methotrexate (1, 2.2%), and colchicine (1, 2.2%). Three cases with Grade 3 severity necessitated permanent ICI discontinuation. Clinical stabilization (24, 54.5%) or remission of the irAIBD (16, 36.3%) was achieved in most cases. One death (2.2%) was attributed to sepsis in a patient with severe irAIBD. Conclusion ICI-associated AIBDs are uncommon but clinically significant complications. Most patients in our cohort continued ICI therapy during management of their irAIBD, while others required temporary or permanent interruption. These findings highlight the importance of prompt recognition and multidisciplinary management of these uncommon toxicities.

ABSTRACT Tissue‐resident memory T cells (TRMs) are a distinct memory T‐cell subset that permanently reside in tissues such as the skin. In chronic immune‐mediated dermatoses, including psoriasis, atopic dermatitis, and vitiligo, TRMs are implicated in site‐specific “disease memory,” contributing to persistence and relapse at previously affected sites. This review synthesizes emerging concepts on TRMs in chronic inflammatory skin diseases and discusses clinical and translational implications, including TRM‐targeted therapies. Original human, animal, or in vitro studies evaluating TRMs in the pathogenesis or persistence of dermatologic diseases were included. In psoriasis, CD8 + TRMs (CD69 + CD103 + ) persisted in clinically healed skin. For atopic dermatitis, both CD4 + and CD8 + TRMs are implicated in maintaining Th2/Th22 inflammation. In vitiligo, autoreactive CD8 + TRMs at lesional margins mediate melanocyte destruction. Across dermatological diseases, TRMs share three core features: persistence in previously affected skin after clinical resolution, rapid reactivation by diverse triggers (stress, autoantigens, allergens, or cytokines) leading to site‐specific recurrence, and relative resistance to conventional therapies. Together, these properties provide a unifying framework linking tissue immune memory to the chronic, relapsing nature of inflammatory skin diseases. However, the dominant TRM pathways vary by disease, reflecting differences in immune polarization and antigen specificity. Targeting TRMs represents a promising strategy for disease control and serves as a biomarker of residual disease or flare. image

We performed a retrospective review of patients with lichen planus pemphigoides (LPP) over almost a 23-year period to gather clinical, histopathological, immunological and treatment-related information and to compare idiopathic LPP with drug-induced LPP. This study represents the largest single-institution case series of LPP to date and includes novel findings related to mucosal involvement, autoantibody profiles and the value of monitoring bullous pemphigoid (BP) autoantibodies in predicting treatment response. This study also includes characteristic histopathological findings that can aid in the diagnosis and differentiation of LPP from BP, in addition to comparisons between idiopathic LPP and drug-induced LPP.