Forty-four cases were submitted representing a broad spectrum of lymphoproliferative disorders (LPDs) encountered in the settings of immunosuppressive and immunomodulatory therapies, various interventions for solid tumor treatment, drug reaction with eosinophilia and systemic symptoms (DRESS), CAR T-cell therapy for B-cell lymphomas, Bruton tyrosine kinase inhibitors (BTKI) for SLL/CLL treatment, ABL-kinase inhibitor dasatinib, and COVID-19 vaccination. The gene discussed is IBTK; the disease is lymphoproliferative syndrome.