IL-2-inducible T-cell kinase deficiency with pulmonary manifestations due to disseminated Epstein-Barr virus infection.

IL-2-inducible T-cell kinase (ITK) deficiency is a rare inherited immunodeficiency disease characterized by homozygous mutations in the ITK gene and the inability to control Epstein-Barr virus (EBV) infection leading to EBV-associated lymphoproliferative disorders of B cell origin. Many aspects of its clinical presentation and immunologic phenotype are still unclear to clinicians. We report on a 14-year-old female patient with complaints of an 8-month history of cough and fever. Imaging studies revealed diffuse pulmonary nodules and mediastinal lymphadenopathy. Transbronchial lung biopsy showed nonmalignant polyclonal B cell proliferation. High titers of EBV DNA were detected by PCR analysis in bronchoalveolar lavage fluid, bone marrow, and blood. Genomic analysis revealed a homozygous single base pair deletion in exon 5 of the ITK gene (c.468delT) in this patient. Treatment with rituximab (anti-CD20 mab) resulted in complete clinical remission with resolution of pulmonary lesions and a negative EBV titer in serum. All patients with EBV-associated lymphoproliferative disorders should be analyzed for mutations in ITK.