Good's Syndrome (a.k.a. Thymoma with immunodeficiency) was first described in 1955. Patients develop a thymoma (tumour of the thymus) and have greatly reduced antibody efficiency, which leads to increased susceptibility to bacterial, viral, and fungal infections.

It's a rare disease, mainly found in the over 40s, which affects several thousand people worldwide each year.

The cause is unknown. and the exact criteria for diagnosing the syndrome have still not been formally agreed.

Fifty-five years after Dr. Good’s original observations on thymoma and hypogammaglobulinemia, the pathogenesis of this primary immunodeficiency syndrome remains incompletely understood.

Source : Good’s syndrome remains a mystery after 55 years: A systematic review of the scientific evidence Clinical Immunology, 2010 Jun; 135(3): 347–363.