Thymoma with immunodeficiency
| Thymoma with immunodeficiency | |
|---|---|
| Synonyms | Good syndrome |
Thymoma with immunodeficiency (also known as "Good syndrome") is a condition that occurs in adults in whom hypogammaglobulinemia, deficient cell-mediated immunity, and benign thymoma may develop almost simultaneously.[1]:86
Good Syndrome (GS) is a rare primary immunodeficiency. It is broadly defined as hypogammaglobulinemia associated with presence of a thymoma. It presents in adulthood with an anterior mediastinal mass and recurrent sinopulmonary infections.
The syndrome has been diagnosed around the globe with a focus in Europe. The incidence of thymoma in the United States is 0.15 cases per 100,000 and of these patients, approximately 6-11% have concurrent hypogammaglobulinemia. It affects men and women equally and typically is diagnosed in the sixth decade of life, much later than other primary immunodeficiencies.
Dr. Robert Good recognized the association between thymoma and hypogammaglobulinemia in 1954. Since then, little has been discovered in regards to its pathogenesis.
Signs and symptoms
A minority of patients are diagnosed with thymoma prior to manifestation of the immunodeficient state. Spindle-cell histology is present in most cases.
Patients with Good Syndrome suffer from both deficient humoral and cellular immunity. Commonly patients suffer from respiratory tract infections. Chronic diarrhea is often related to villous atrophy rather than infection.
Good Syndrome is often associated with other autoimmune conditions including pure red cell aplasia and myasthenia gravis. Overall there is a degree of hypogammaglobulinemia, a large percentage will have autoantibodies present in their serum. It is theorized that the presence of thymoma may inhibit the thymus’s normal role in production of self-tolerant T lymphocytes. These T-lymphocytes may then attack the B cell precursors in the marrow, preventing maturation and ultimately resulting in hypogammaglobulinemia.
Pathogenesis
While the cause of Good Syndrome is unknown, it is thought to be an autoimmune process affecting the bone marrow.
Diagnosis
Definition
There are no formal diagnostic criteria and many informal definitions exist. Most commonly thymoma is present with mixed humoral and cellular immune deficiency. T and B cells are both depleted so patients suffer from both encapsulated organisms as well as opportunistic infections. Some have defined GS as a subset of common variable immunodeficiency (CVID). Unlike CVID, there are reduced B cells in the periphery in GS.
More generally it can be defined as an adult-onset primary immunodeficiency associated with thymoma, hypogammaglobulinemia, diminished B and T cells, and inverted CD4/CD8+ ratio.
Treatment
The mainstay of treatment consists of thymectomy and immunoglobulin replacement with intravenous immunoglobulin. Immunodeficiency does not resolve after thymectomy. To treat the autoimmune component of the disease, immunosuppression is sometimes used and it is often challenging to determine if a patient’s symptoms are infectious or autoimmune.
Patients should have serological testing for antibodies to toxoplasma and cytomegalovirus. If receiving a blood transfusion, CMV negative blood should be used in those with negative serological testing. Live vaccines should also be avoided. The Centers for Disease Control and Prevention recommend pneumococcal, meningococcal, and Hib vaccination in those with diminished humoral and cell-mediated immunity.
Some have advocated treating prophylactically with trimethoprim-sulfamethoxazole if CD4 counts are lower than 200 cells/mm^3, similar to HIV/AIDS patients.
See also
References
External links
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