Thymic Dysplasia
Definition
- Congenital architectural changes of the thymus associated with immunodeficiency
Alternate/Historical Names
- Thymic aplasia
- Thymic hypoplasia
Diagnostic Criteria
- Lack of lobular architecture
- Even involuted normal thymus retains lobular pattern
- Lack of defined cortical and medullary zones
- Even involuted cortex is usually distinguishable from medulla
- Hassal corpuscles usually absent
- Few or no lymphocytes
- May also be lacking in involution
- No precise correlation of pattern with clinical syndrome
- Thymus in Down syndrome retains lobularity and Hassal corpuscles
- Thymic aplasia refers to absence of any formed thymus
- Seen in DiGeorge syndrome
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
