Immunodeficiency and thymoma in Good syndrome: Two sides of the same coin

•Good Syndrome is a complex disease integrating a medical history of thymoma and either humoral and/or cellular immunodeficiency.•Recurrent infections, autoimmunity, paraneoplastic syndromes, and aberrations immunological profile are the main clinical manifestations of Good syndrome.•Patients with recurrent respiratory infections and de novo autoimmune manifestations could benefit from early screening of thymoma and immunodeficiency.•Understanding the possible discordances in clinical presentation and immunological alterations is key to prevent misdiagnosis and complications.•There are no current guidelines for the diagnosis and management of patients with Good Syndrome. Good Syndrome is a rare clinical entity first described as the conjunction of thymoma and hypogammaglobulinemia, and more recently depicted as a complex disease integrating a medical history of thymoma with humoral immunodeficiency (more accurately stated: hypogammaglobulinemia) with or without cellular immunodeficiency, recurrent infections, autoimmunity, paraneoplastic syndromes and diverse aberrations in the immunological profile. This condition has an ominous prognosis with a high mortality rate secondary to recalcitrant infectious diseases. Understanding the possible discordances in clinical presentation and the temporal relationship between manifestations and immunological alterations is key to prevent misdiagnosis and complications. To this end, here we provide two illustrative patients with Good Syndrome that share common clinical manifestations and yet show unique and opposed immunological profiles, thereby highlighting the pivotal interest of a comprehensive immunological profiling in these patients. We conducted a thorough review of existing literature on the elusive molecular mechanisms underlying the syndrome and provide a clinical assessment algorithm to facilitate the management of these challenging patients.