Lehman, Julia S

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.

This article describes clinical, serologic, and histopathologic features of the first North American cohort of patients with positive anti-p200 serology identified at Mayo Clinic, Rochester, Minnesota, USA and Beutner Laboratories, Buffalo, New York, USA. Forty-seven patients were identified with positive p200 laminin beta 4 autoantibodies, detected with either immunoglobulin (Ig)G or IgG4 modified indirect immunofluorescence on HEK293 cells transfected with recombinant laminin beta.

Importance Contemporary guidelines recommend sentinel lymph node biopsy (SLNB) for patients with melanoma with predicted risk of SLN metastasis greater than 10% and consideration of SLNB when the risk is 5% to 10%. A gene expression profile (GEP)–based test that can accurately identify patients with a low risk of SLN metastasis would refine selection for SLNB. Objective To establish the predictive capability of the combined clinicopathological factors and GEP (CP-GEP) test to identify patients with primary cutaneous melanoma who can safely forgo SLNB and to investigate the prognostic value of CP-GEP regarding the outcome in patients with cutaneous melanoma after a negative SLNB (not reported herein). Design, Setting, and Participants This prognostic study was conducted from September 2021 to June 2024 at 9 academic medical centers with experienced melanoma surgeons. Included were patients with biopsy-proven invasive cutaneous melanoma with T1 to T3 tumors and clinically negative regional LNs. All patients were deemed candidates for SLNB using standard clinical criteria. GEP was performed on formalin-fixed, paraffin-embedded tissue from the primary melanoma biopsy. Analyses were performed from December 2024 to August 2025. Intervention CP-GEP testing to determine risk of having a positive SLNB in patients with T1 to T3 cutaneous melanoma who were considered appropriate candidates for the procedure based on standard clinical parameters. Main Outcomes and Measures CP-GEP results were reported as low risk or high risk; the primary outcome measure was negative predictive value (NPV) in low-risk cases. Analyses included NPV assessment by tumor (T) subcategory, primary site, and age. Results A total of 1761 patients (median [IQR] age, 64 [53-72] years; 997 male [56.6%]) underwent SLNB (310 [17.6%] SLN positive) and had a successful CP-GEP test; GEP was successful in 97.7% of samples. A total of 651 patients (37.0%) were considered low risk by CP-GEP. Among low-risk cases, 46 (7.1%) were SLN positive, and NPV was 92.9% (95% CI, 90.7%-94.8%). High-risk cases had a 23.8% (264 of 1110) SLN-positive rate. The percentage of cases with low-risk CP-GEP declined with increasing T category (T1 = 346 of 507 [68.2%]; T2 = 295 of 897 [32.9%]; T3 = 10 of 357 [2.8%]). CP-GEP results were consistent in discriminating SLN-positive rates across primary sites, histologic subtypes, and mitotic count categories. In 2 large subsets, clinical stage IB (n = 1187) and patients 65 years and older (n = 832), 6.5% (95% CI, 4.6%-8.8%) of low-risk clinical stage IB cases and 6.6% (95% CI, 4.2%-9.7%) of all low-risk cases in patients 65 years and older were SLN positive vs 18.3% (95% CI, 15.3%-21.6%) and 20.3% (95% CI, 16.8%-24.2%) for high-risk cases, respectively. Conclusions and Relevance In this multicenter, prospective, blinded, prognostic study, the CP-GEP test reliably identified patients with melanoma with less than 10% SLN metastasis risk. SLN metastasis rates were approximately 3-fold greater for high-risk vs low-risk CP-GEP cases. In appropriately selected patients, the CP-GEP test may add value for shared patient-surgeon decision-making.

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.

ABSTRACTBackgroundIntercellular IgG4 deposition is variably present on DIF in patients with pemphigus. Whether this feature has clinical, serologic, or histopathologic correlates was unknown.MethodsWe identified 34 patients with pemphigus who had 55 DIF specimens reported to show intercellular IgG, IgG4, and/or C3 deposition (8/22/2017–11/30/2023). Patients and biopsies were stratified by intercellular IgG4 status. Clinical and serologic data were extracted from electronic records, and corresponding biopsy slides were reviewed for histopathologic findings.ResultsAmong the 34 patients with pemphigus, patients with positive IgG4 were significantly more likely to have detectable serum anti‐desmoglein 1/3 antibodies by ELISA (p = 0.014 and p = 0.030, respectively). Paraneoplastic pemphigus (PNP) was more frequent in the IgG4‐negative group (p = 0.037), particularly among patients with ocular involvement. Of 55 DIF biopsy specimens meeting inclusion criteria, 52 (94.5%) had intercellular IgG deposition and 42 (76.4%) had intercellular IgG4 on DIF. Compared to IgG4‐negative specimens, IgG4‐positive specimens were significantly more likely to represent a vesiculobullous lesion (p = 0.024), to be derived from the trunk (p = 0.047), to show histologic acantholysis (p = 0.019) and to lack lichenoid inflammation (p = 0.0004).ConclusionFor pemphigus, DIF IgG4 status correlated with ocular involvement, the clinical morphology selected for biopsy, the likelihood of detecting circulating desmoglein antibodies, the presence of specific histopathologic features such as acantholysis and lichenoid inflammation, and the likelihood of having a final diagnosis of PNP. Further studies are needed to determine whether the presence of tissue‐bound intercellular IgG4 antibodies correlates with particular disease variants or lesion‐specific characteristics.

ABSTRACTBackground/ObjectivesImmune‐mediated skin disorders, such as immunobullous dermatoses and leukocytoclastic vasculitis, rarely affect children. While direct immunofluorescence (DIF) biopsy is a standard diagnostic tool, limited data exist on pediatric DIF patterns, rates of positivity, pretest diagnostic concordance, and the relevance of biopsy site. This study sought to address these gaps.MethodsDIF data from all skin and mucosal specimens interpreted at Mayo Clinic's reference immunodermatology laboratory for patients aged 0–18 years (August 22, 2017 to November 30, 2023) were reviewed. DIF results were classified as positive if a characteristic pattern was seen and negative if the findings were negative or nondiagnostic.ResultsOf 986 pediatric DIF studies, 153 (15.5%) were positive and comparable to adult positivity rates (20.9%) during the same period. The most frequent DIF patterns were IgA‐predominant vasculitis (N = 85/153; 55.5%) and lichenoid tissue reaction (N = 21/153;13.7%). Concordance between pretest diagnosis and positive DIF results was highest for linear IgA bullous dermatosis (N = 7/7; 100%) and dermatitis herpetiformis (N = 6/6; 100%). Excluding these entities, DIF changed the pretest diagnosis in 16.7% (N = 19/114) of cases. While lower extremity biopsies were initially more likely to yield positive DIF results, this association disappeared when IgA vasculitis cases were excluded.ConclusionThe most frequent DIF pattern in children was that of IgA‐predominant vasculitis. Pediatric DIF positivity rates closely mirrored those of adults, supporting similar biopsy thresholds. DIF results differed from the pretest impression in a substantial percentage, supporting the value of DIF in select situations in the pediatric population. After controlling for IgA vasculitis, biopsy site was not associated with DIF positivity.