Background/Objectives: Immediate-type hypersensitivity reactions (HSRs) to proton pump inhibitors (PPIs) represent a clinically relevant adverse drug reaction and pose diagnostic and management challenges, including variable cross-reactivity (CR). Drug provocation testing (DPT) is the diagnostic gold standard, but real-life use after testing remains uncertain. This study aimed to describe clinical features, diagnostic outcomes, CR profiles, and real-life PPI use in patients with immediate-type PPI hypersensitivity. Methods: Single-center ambispective study of 40 patients evaluated for immediate-type PPI HSRs (2014–2023). Index reactions, culprit PPI, and skin test/DPT results were recorded retrospectively. Patients tolerating an alternative PPI on DPT were followed prospectively; real-life tolerance and use were assessed by structured telephone interview. Results: Among 40 patients (87.5% female; mean age 48 years), lansoprazole was the most frequent culprit (50%); anaphylaxis occurred in 65%. Skin tests were positive in 25% (n = 9), and a shorter interval from reaction to testing was associated with positivity (p = 0.025). CR was detected in 25% (n = 10), most often between lansoprazole and pantoprazole. All 29 patients undergoing DPT tolerated at least one alternative PPI. In real-life follow-up (n = 27), 11 (40.7%) restarted PPIs without recurrence; 1 (3.7%) developed a mild cutaneous reaction despite negative testing. Fifteen (55.6%) did not restart therapy; 4 (14.8%) cited drug-related anxiety or physician-advised avoidance. Conclusions: In immediate-type PPI hypersensitivity, skin test sensitivity appears time-dependent, supporting early evaluation. DPT identifies safe alternatives, yet behavioral and clinician-related barriers limit real-life implementation; addressing these barriers is essential to optimize PPI allergy management.

Resistance to Thyroid Hormone Complicating the Management of Papillary Thyroid Carcinoma - Gazi Medical Journal

Background: X-linked immunodeficiency with magnesium defect, Epstein–Barr virus (EBV) infection, and neoplasia (XMEN) disease is a rare inborn error of immunity caused by loss-of-function mutations in MAGT1, leading to impaired N-linked glycosylation. Although chronic EBV viremia is a hallmark of XMEN disease, the mechanisms underlying its marked clinical heterogeneity remain poorly understood. Methods: We performed an in-depth clinical, immunological, and genetic characterization of two siblings carrying a pathogenic MAGT1 variant (c.369_370insCC; p.Gly124fs), validated and deposited in ClinVar (SCV007293792). Assessments included whole-exome sequencing, multiparametric flow cytometry focusing on NKG2D expression, and longitudinal clinical follow-up. Results: Despite shared absence of NKG2D expression, the siblings exhibited strikingly divergent phenotypes. One sibling developed progressive neurodegeneration with central nervous system atrophy. The other presented with a complex immuno-hematologic phenotype, including EBV-positive Hodgkin lymphoma, recurrent autoimmune cytopenias, and lymphoma-associated thrombotic microangiopathy, representing a novel clinical association in XMEN disease. Comparative immunophenotyping revealed shared defects in B-cell maturation but distinct T-cell differentiation patterns. To contextualize neurological variability, we propose a descriptive, hypothesis-generating three-category conceptual classification comprising early-onset neurodevelopmental forms, adult-onset neurodegenerative manifestations, and secondary immune-mediated or vascular involvement of the nervous system. Conclusions: These findings demonstrate profound intrafamilial heterogeneity in XMEN disease and suggest a model in which modifier-sensitive factors influence organ-specific disease expression. The observation of lymphoma-associated thrombotic microangiopathy and the proposed descriptive neurological classification provide a conceptual framework that may help guide tailored, multidisciplinary surveillance beyond the primary genetic defect.