The Thymus : Diagnostic Imaging, Functions, and Pathologic Anatomy

This book discusses in detail the use and value of the various imaging procedures in respect of all thymic diseases. Due consideration is given to the normal thymus, and pathologic anatomy, clinical symptoms, therapy, and prognosis, all receive extensive coverage that reflects the present state of our knowledge.

1 Introduction — Historical Background.- 2 Anatomy and Embryology of the Thymus.- 2.1 Embryology.- 2.2 Normal Anatomy.- 2.3 Involution.- References.- 3 Immunologic Function of the Thymus.- 3.1 Historical Overview.- 3.2 T Cell Molecules in Antigen Recognition.- 3.2.1 Accessory Molecules.- 3.3 Ontogeny of T Cells.- 3.3.1 Thymocyte Precursors.- 3.3.2 TCR Rearrangements.- 3.3.3 Maturation into Functional T Cells.- 3.3.4 Factors Governing T Cell Development Within the Thymus.- 3.4 Cellular Selection in the Thymus.- 3.5 Clinical Aspects.- 3.6 Summary.- References.- 4 Imaging Procedures for Visualization of the Thymus.- 4.1 Plain Film Diagnostics E.Walter and E.Willich.- 4.1.1 Chest Radiography in Two Planes.- 4.1.2 Fluoroscopy.- 4.2 Conventional Tomography.- 4.3 Ultrasonography.- 4.4 Computed Tomography.- 4.5 Magnetic Resonance Imaging W.R.Webb and G.deGeer.- 4.5.1 Principles of Magnetic Resonance Imaging.- 4.5.2 Image Production.- 4.5.3 Normal Appearances.- 4.5.4 Image Contrast and Interpretation.- 4.5.5 MRI Diagnosis of Mediastinal Masses.- 4.5.6 Image Acquisition and ECG Gating.- 4.5.7 Characterization of Mediastinal Masses.- 4.6 Nuclear Medicine E.Walter and E.Willich.- 4.6.1 67 Gallium Citrate.- 4.6.2 75 Selenium Methionine.- 4.6.3 99m Technetium Pertechnetate.- 4.7 Esophagography.- 4.8 Angiography.- 4.8.1 Arteriography.- 4.8.2 Angiocardiography.- 4.8.3 Phlebography and Superior Venacavography.- 4.9 Obsolete Methods.- 4.9.1 Kymography.- 4.9.2 Pneumomediastinography.- 4.10 Supplementary Procedures (Mediastinography, Bronchoscopy, Bronchography) E.Willich.- References.- 5 Diagnostic Imaging of the Normal Thymus.- 5.1 Conventional Diagnostics in Children E.Willich and E.Walter.- 5.1.1 Newborns and Infants.- 5.1.2 Preschool Age to Adolescence.- 5.1.3 Adults.- 5.2 Ultrasonography.- 5.2.1 Children.- 5.2.2 Adults.- 5.3 Computed Tomography E.Walter.- 5.4 Magnetic Resonance Imaging W.R.Webb and G.deGeer.- 5.4.1 Children.- 5.4.2 Adults.- 5.5 Invasive Procedures (Pneumomediastinography, Arteriography, Phlebography) E.Walter.- 5.6 Measurement of the Size of the Thymus E.Willich.- 5.6.1 Radiographic Method.- 5.6.2 Computed Tomography.- 5.6.3 Magnetic Resonance Imaging W.R.Webb and G.deGeer.- References.- 6 Acute and Stress-Induced Involution of the Thymus.- 6.1 Acute Endogenous Involution of the Thymus.- 6.2 Exogenous Involution of the Thymus: the Steroid Test.- 6.3 Transplacental Influence of Steroids on the Premature Infant’s Thymus.- References.- 7 Developmental Abnormalities of the Thymus.- 7.1 Aplasia, Hypoplasia, and Dysplasia E.Willich and E.Walter.- 7.2 Dystopia.- 7.2.1 Cervical and Superior Mediastinum.- 7.2.2 Middle Mediastinum.- 7.2.3 Posterior Mediastinum.- 7.2.4 Miscellaneous.- References.- 7.3 Persistent Thymus E.Willich.- 7.3.1 Introduction.- 7.3.2 Pathophysiologic Causes.- 7.3.3 Clinical Features.- 7.3.4 Imaging Methods.- 7.3.5 Differential Diagnosis.- References.- 7.4 Hyperplasia.- 7.4.1 Introduction.- 7.4.2 Pathologic Features W.J.Hofmann and H.F. Otto.- 7.4.2.1 True Thymic Hyperplasia.- 7.4.2.2 Thymic Hyperplasia with Massive Enlargement of the Gland.- 7.4.2.3 Thymic Rebound in Childhood and Adolescence.- 7.4.2.4 True Thymic Hyperplasia in Association with Other Diseases.- 7.4.2.5 Lymphofollicular Hyperplasia of the Thymus.- 7.4.3 Clinical Features E.Willich.- 7.4.3.1 Asymptomatic Thymic Hyperplasia.- 7.4.3.2 Symptomatic Thymic Hyperplasia.- 7.4.4 Associated Diseases.- 7.4.5 Imaging Procedures and Findings.- 7.4.6 Regenerative Hyperplasia (Regrowth, Rebound Phenomenon).- 7.4.7 Differential Diagnosis.- 7.4.8 Therapy.- 7.4.9 Follow-up.- References.- 8 Tumors of the Thymus.- 8.1 Introduction E.Walter.- 8.2 Epithelial Tumors of the Thymus.- 8.2.1 Pathologic Features W.J.Hofmann and H.F. Otto.- 8.2.1.1 Macroscopic Appearance.- 8.2.1.2 Histologic Appearance.- 8.2.1.3 Classification.- 8.2.1.4 Immunohistology.- 8.2.1.5 Clinicopathologic Correlations.- References.- 8.2.2 Encapsulated and Invasive Thymomas E.Walter.- 8.2.2.1 Occurrence and Clinical Symptoms.- 8.2.2.2 Association of Thymoma with Other Syndromes and Diseases.- 8.2.2.3 Diagnosis with Imaging Procedures.- 8.2.2.4 Differential Diagnosis.- 8.2.2.5 Relative Value of the Imaging Procedures.- 8.2.2.6 Therapy and Prognosis.- References.- 8.2.3 Carcinoma of the Thymus.- 8.2.3.1 Occurrence and Clinical Symptoms.- 8.2.3.2 Diagnosis with Imaging Procedures.- 8.2.3.3 Differential Diagnosis.- 8.2.3.4 Relative Value of the Imaging Procedures.- 8.2.3.5 Therapy and Prognosis.- References.- 8.3 Carcinoid Tumors of the Thymus.- 8.3.1 Pathologic Features W.J.Hofmann and H.F. Otto.- 8.3.2 Occurrence and Clinical Symptoms E.Walter.- 8.3.2.1 Occurrence.- 8.3.2.2 Clinical Symptoms.- 8.3.3 Diagnosis with Imaging Procedures.- 8.3.4 Differential Diagnosis.- 8.3.5 Relative Value of the Imaging Procedures.- 8.3.6 Therapy and Prognosis.- References.- 8.4 Thymic Involvement in Malignant Lymphomas and Leukemia E.Willich and E.Walter.- 8.4.1 Pathologic Features W. J. Hofmann and H. F. Otto.- 8.4.2 Hodgkin’s Disease E.Willich and E.Walter.- 8.4.2.1 Occurrence.- 8.4.2.2 Clinical Symptoms.- 8.4.2.3 Diagnosis with Imaging Procedures.- 8.4.2.4 Hodgkin’s Disease of the Thymus Before and After Radiotherapy and Chemotherapy E.Walter and E.Willich.- 8.4.3 Non-Hodgkin’s Lymphoma.- 8.4.4 Leukemia.- 8.4.5 Non-Hodgkin’s Lymphoma and Leukemia with Thymic Involvement, During and After Radiotherapy and Chemotherapy.- 8.4.6 Differential Diagnosis E.Walter.- 8.4.7 Relative Value of the Imaging Procedures.- References.- 8.5 Mesenchymal Tumors (Thymolipoma) E.Walter.- 8.5.1 Pathologic Features W. J. Hofmann and H. F. Otto.- 8.5.2 Occurrence and Clinical Symptoms E.Walter.- 8.5.2.1 Occurrence.- 8.5.2.2 Clinical Symptoms.- 8.5.3 Diagnosis with Imaging Procedures.- 8.5.4 Differential Diagnosis.- 8.5.5 Relative Value of Imaging Procedures.- 8.5.6 Therapy and Prognosis.- References.- 8.6 Germ Cell Tumors and Teratomas E.Walter.- 8.6.1 Pathologic Anatomy W.J.Hofmann and H.F. Otto.- 8.6.2 Seminoma E.Walter.- 8.6.2.1 Occurrence and Clinical Symptoms.- 8.6.2.2 Diagnosis with Imaging Procedures.- 8.6.2.3 Differential Diagnosis and Relative Value of the Imaging Procedures.- 8.6.2.4 Therapy and Prognosis.- 8.6.3 Nonseminomatous, Pure or Mixed Germ Cell Tumors.- 8.6.3.1 Occurrence and Clinical Symptoms.- 8.6.3.2 Diagnosis with Imaging Procedures.- 8.6.3.3 Differential Diagnosis and Relative Value of the Imaging Procedures.- 8.6.3.4 Therapy and Prognosis.- References.- 8.7 Rare Tumors of the Thymus.- 8.7.1 Hemangioma of the Thymus.- 8.7.2 Choristoma of the Thymus.- References.- 8.8 Metastases to the Thymus.- Reference.- 9 Tumor-like (Nonneoplastic) Conditions of the Thymus and/or Mediastinum.- 9.1 Thymogenic Cysts.- 9.1.1 Pathologic Anatomy W.J.Hofmann and H.F. Otto.- 9.1.2 Occurrence and Clinical Symptoms E.Walter and E. Willich.- 9.1.3 Diagnosis with Imaging Procedures.- 9.1.4 Differential Diagnosis.- 9.1.5 Relative Value of the Imaging Procedures.- 9.1.6 Therapy and Prognosis.- 9.2 Hydatidosis of the Thymus.- 9.3 Tuberculoma of the Thymus.- 9.4 Histiocytosis X of the Thymus.- References.- 10 Trauma and Hemorrhage of the Thymus.- 10.1 Trauma.- 10.2 Hemorrhage.- References.- 11 Thymus and Myasthenia Gravis.- 11.1 Definition of Myasthenia Gravis H.Wlethölter.- 11.2 Clinical Manifestation.- 11.2.1 Symptoms and Signs.- 11.2.2 Classification.- 11.2.3 Clinical Examination.- 11.2.4 Prognosis.- 11.3 Associated Thymic Changes.- 11.3.1 Association of Thymic Changes with Other Diseases.- 11.4 Pathogenesis.- 11.5 Autoimmune Origin.- 11.6 Diagnosis.- 11.6.1 Radiological Diagnosis E.Willich and E.Walter.- 11.7 Treatment H.Wlethölter.- References.