Atypical Presentation in X-linked Immunodeficiency With Magnesium Defect, Epstein-Barr Virus (EBV) Infection, and Neoplasia (XMEN) Disease: A Case Report and Review of Emerging Therapies

X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection, and neoplasia (XMEN) is a rare primary immunodeficiency caused by MAGT1 mutations. These mutations impair N-linked glycosylation and magnesium-dependent signaling in T cells, disrupting immune surveillance. XMEN typically presents with chronic Epstein-Barr virus (EBV) viremia, lymphoproliferative disease, and viral infections, although phenotypic variability is increasingly recognized. A seven-year-old male presented at age five with bilateral conjunctival hemorrhages and petechiae and was found to have severe thrombocytopenia (platelet count: 4,000/µL). Initial treatment for presumed idiopathic thrombocytopenia (ITP) with idiopathic thrombocytopenic purpura (IVIG) and corticosteroids yielded minimal improvement. Bone marrow biopsy excluded malignancy, and he was maintained on romiplostim with variable platelet recovery. Two years later, he was evaluated by genetics due to persistent ITP, steroid side effects, and disseminated molluscum contagiosum. Genetic testing revealed a pathogenic hemizygous deletion of exons 2-10 in MAGT1, confirmed by chromosomal microarray. This deletion is consistent with XMEN disease. Family testing showed no mutation in his two full brothers, suggesting a de novo variant. Despite low platelet counts and elevated liver enzymes, he remained free of systemic infections and EBV-related complications. Magnesium supplementation resulted in moderate improvement of molluscum contagiosum lesions, but thrombocytopenia persisted. This case illustrates an atypical presentation of XMEN disease, with isolated thrombocytopenia and cutaneous viral infection in the absence of EBV viremia or lymphoproliferative disease. It supports a broader clinical spectrum for XMEN and underscores the need for continued research into genotype-phenotype correlations and targeted therapeutic approaches.