[Good syndrome: a rare, unusual immunodeficiency condition].

Good syndrome is an infrequent and unique clinical entity of associated thymoma and immunodeficiency, first described almost 70 years ago. It is characterized by increased susceptibility to recurrent invasive bacterial and opportunistic infections as well as autoimmune and malignant diseases with an omnious prognosis. The affected patients are mainly middle-aged persons. The most consistent immunological abnormalities are hypogammaglobulinemia and reduced/absent B cells. More recently it was classified as an acquired combined (T, B) immunodeficiency and labelled as a phenocopy. This complex immunocompromised condition can lead to heterogenous clinical phenotypes, making the diagnosis rather challenging. The thymoma is mainly benign, and an incidental finding. Since the thymus plays a critical role in the development of the immune system, the altered tissue structure and microenvironment in thymoma can both predispose to manifestation of immunodeficiency and autoimmunity. The etiopathogenesis of the disease is still unclear, but it is assumed that epigenetic and acquired genetic factors can be highly responsible for its evolvement. Currently there is no specific therapy for Good syndrome. In addition to thymectomy, control of infections, possibly secondary prevention, and regular immunoglobulin replacement are recommended. Orv Hetil. 2023; 164(22): 859-863.