RESUMO
BACKGROUND: Immunodeficiency with a thymoma (Good's syndrome) is a rare condition occurring in patients with adult-onset hypogammaglobulinemia that is progressive after the removal of thymoma. Recently, we encountered a patient with Good's syndrome who suddenly developed opportunistic encephalitis 4 years after the resection of thymoma without a history of infectious complications. CASE PRESENTATION: A 58-year-old man, who underwent surgery to remove a thymoma at the age of 54, was admitted because of speech difficulties. A brain MRI showed multiple lesions involving the frontal lobes, but the CSF finding was normal. Acyclovir was empirically administered, and fever as well as his neurological symptoms fully recovered within a few days. However, 1 week after admission, motor aphasia and mild right hemiparesis reappeared. MRI showed that the lesion involving the left cingulate gyrus expanded in size, and revealed an abnormal signal intensity lesion in the left corona radiata. Laboratory examination found increased CMV pp65 antigen-positive lymphocytes in serum. Antiviral therapy using ganciclovir and immunoglobulin replacement therapy was started. The patient has since been free from any neurological symptoms for 1 year, and lesions demonstrated by MRI are gradually improving. CONCLUSION: Early recognition of this rare condition and prompt initiation of therapy are crucially important. Awareness of immunodeficiency in a patient after removal of thymoma may help neurologists to consider the possibility that opportunistic infection may be the cause of cerebral lesions.