RESUMEN
Good's syndrome (thymoma with immunodeficiency) is a rare cause of combined B-cell and T-cell immunodeficiency in adults. We present here a case of Good's syndrome involving a 52 year-old man with an ABO blood group abnormality. He had undergone surgery for thymoma with myasthenia gravis 27 years ago. He also had a history of pulmonary tuberculosis, herpes zoster and pure red cell aplasia. On admission, he was suspected of having pneumonia, and S. pneumoniae was isolated from blood culture. The immunoglobulin levels were markedly decreased. Lymphocyte subset analysis revealed the absence of CD19+ B cells. The result of ABO typing showed a normal strong reaction on the cell typing, but a relatively weak reaction on the serum typing. Therefore, we performed ABO genotyping to confirm his ABO type, which was revealed to be B/O1 . This case suggests that ABO typing should be performed when the diagnosis of Good's syndrome is made. Moreover, Good's syndrome (thymoma with hypogammaglobulinemia) should be considered and evaluated for in patients with a weak ABO reverse type.