Overview

The thymus is a primary lymphoid organ where T lymphocytes mature and undergo selection to ensure self tolerance. It is most active in childhood and involutes with age leaving residual fatty tissue in adults. Thymic pathology affects immune competence and may present with masses.

Thymic Structure

The thymus contains cortical and medullary regions supporting thymocyte maturation and selection. Hassall corpuscles and epithelial cells contribute to thymic microenvironment. Thymic size and morphology vary with age and stress.

Clinical Relevance

Thymic hyperplasia thymoma and thymic carcinoma are clinical entities requiring imaging and sometimes biopsy. Thymic abnormalities associate with myasthenia gravis and paraneoplastic syndromes. CT and MRI characterize thymic lesions and guide management.

Thymic Imaging

CT and MRI evaluate thymic size morphology and focal lesions while PET may assess metabolic activity. Imaging differentiates normal involution from pathologic enlargement. Multidisciplinary evaluation guides surgical and medical therapy.