Journal Menu

Thymus Gland: Functions and Dysfunctions in Children

Țurcanu Tamara*, and Dolapciu Elena

Department of Pediatrics, "Nicolae Testemițanu" State University of Medicine and Pharmacy, Republic of Moldova

*Corresponding author

*Țurcanu Tamara, Department of Pediatrics, “Nicolae Testemițanu” State University of Medicine and Pharmacy, Republic of Moldova

Abstract

Introduction: The thymus is a key organ in the development of the immune system in children, being involved in T lymphocyte maturation and the establishment of immunological tolerance.
Objective: This review aims to synthesize current data from the literature on the functions and dysfunctions of the thymus in children, with the goal of supporting pediatric clinical practice.
Methods: A narrative literature review was conducted using the PubMed, Scopus, and Google Scholar databases. Keywords used included: “thymus”, functions”, “thymic dysfunctions”, “children”.
Results: The thymus plays both immunological and endocrine roles. Thymic dysfunctions can be either congenital or acquired, and may present as hypoplasia, hyperplasia, or tumor formation.
Conclusion: Improved understanding of thymic physiology and pathology is essential to avoid unnecessary investigations and to support appropriate clinical management.

Keywords: Thymus, Functions, Thymic Dysfunctions, Child

Introduction

The thymus is a primary lymphoid organ located in the anterior mediastinum, crucial for immune development in early life. It is the site of T lymphocyte maturation, enabling the immune system to differentiate between self and non-self-antigens. The thymus also plays a central role in the establishment of central and peripheral immunological tolerance, helping to prevent autoimmune diseases. Although the thymus undergoes physiological involution with age, it is highly active in the pediatric population, especially in infancy and early childhood.

Materials and Methods

A narrative review was performed based on literature published between 2000 and 2024. The electronic databases PubMed, Scopus, and Google Scholar were searched using combinations of the following keywords: “thymus”, “functions”, “thymic dysfunctions”, and “children”. Studies included review articles, clinical studies, and relevant case reports published in English or Romanian. Articles focused on thymic structure, development, function, and pathology in children were selected.

  1. Results

3.1. Functions of the Thymus

  • Immunological Function: The thymus serves as the primary site for T cell maturation. It ensures selection of functional T lymphocytes through two processes:
    • Positive selection, which ensures T cells recognize self-MHC molecules;
    • Negative selection, which eliminates autoreactive T cells, preventing autoimmunity.
  • Immunological Tolerance: By eliminating self-reactive lymphocytes, the thymus contributes to immune tolerance both centrally and peripherally.
  • Endocrine Function: The thymus secretes hormones such as thymopoietin, thymosin, and thymulin, which influence lymphocyte differentiation and may regulate tissue metabolism and neuroendocrine functions.

3.2. Thymic Dysfunctions

Congenital Disorders:

  • Aplasia (athymia): Absence of thymic tissue, as seen in DiGeorge syndrome;
  • Hypoplasia: Underdevelopment of the thymus;
  • Congenital thymic hyperplasia;
  • Ectopic thymus: Thymic tissue located outside its usual anatomical position.

Acquired Disorders:

▪ Thymic hyperplasia: May be true or lymphoid hyperplasia:

▪True hyperplasia: Uniform enlargement of the thymus without architectural distortion;

▪Lymphoid hyperplasia: Characterized by increased lymphoid follicles, often in association with

Autoimmune conditions or post-infectious states.

Lymphoid hyperplasia includes three main clinico-pathological forms:

▪Massive thymic hyperplasia

▪Rebound hyperplasia – occurs after stress (infection, corticosteroid therapy, malnutrition) and reflects immune system recovery

Hyperplasia associated with endocrine disorders

▪Thymic tumors: Rare in children, most commonly epithelial in origin (e.g., thymus’s),

accounting for 0.2–1.5% of all malignancies.

Discussion

Rebound thymic hyperplasia is commonly observed in infants and young children following acute infectious or nutritional stress. It is typically benign and self-limited, yet often misinterpreted as a mediastinal mass, leading to unnecessary imaging, biopsies, or even surgical interventions.Proper differentiation between benign thymus hyperplasia and thymus neoplasms (e.g., thymoma, cysts) is critical and should rely on imaging (CT, MRI) and clinical context.
Massive thymus hyperplasia, although rare, can mimic malignancy and requires careful monitoring. Thymes dysfunctions associated with congenital syndromes (e.g., Di George syndrome) pose significant immunological challenges and necessitate multidisciplinary management. Understanding the structural and functional dynamics of the thymus in pediatrics helps clinicians avoid diagnostic errors, reduce unnecessary procedures, and initiate appropriate therapy when required.

Conclusion

The thymus is a vital organ for the maturation and regulation of the immune system in early childhood.2. Recognition of its physiological functions and potential dysfunctions is crucial for pediatricians. 3. Awareness of conditions such as rebound hyperplasia, congenital hypoplasia, and rare thyme tumors can improve diagnostic accuracy, minimize unnecessary investigations, and guide optimal clinical decision-making.

REFERENCES

  1. Forchielli ML, Walker WA (2005) The effect of nutritional status on the Development of the immune system. Current Opinion in Allergy and Clinical Immunology, 5(2): 191–195.
  2. Cathleen Collins (2020) l”Congenital Athymia: Genetic Etiologies, Clinical Manifestations, Diagnosis, and Treatment”.J Clin Immunologie.
  3. Markert ML (2009) Thymus transplantation in complete DiGeorge syndrome. Immunol Res 44(1-3): 61–70.
  4. Paediatric Tumours WHO Classification of Tumours, 5th Edition, Volume 7 WHO Classification of Tumours Editorial Board 2023ISBN-13 .978-92-832-4510-0
  5. Savino W, Dardenne M (2000) Neuroendocrine control of thymus physiology. Endocr Rev 21(4): 412–443.
  6. Srinivasan J, Lancaster JN, Singarapu N (2021) Age-Related Changes in Thymic Central Tolerance. Immunol 12: 676236.
  7. Tomaszek SC (2014) Thymic hyperplasia: clinical and radiologic considerations. J Thorac Oncol 9(2): E12–E14.
  8. Rovada I.Minyailova N.N (2023)”Evolutionary aspects of thymology in pediatric practice” Medical Immunology (Russia). 25: 1.
  9. Revathi Muthu, Jaishree Vasudevan, Jeffrey Skaria Joseph (2024) Comparison of thymus size in Normal versus malnourished children Ro J Pediatr 73(4).
  10. Smita Manchanda, Ashu S Bhalla (2017) “Imaging of the pediatric thymus: Clinicoradiologic approach” World J Clin Pediatr. 6(1):10–23.
  11. Zhuang H (2021) Rebound thymic hyperplasia: imaging findings and clinical significance. Pediatr Radiol 51(3): 357–366.

JCMCRI
ISSN: 3064-8025

Journal of Clinical & Medical Case Reports, Images (JCMCRI) ISSN: 3064-8025 is a peer-reviewed journal dedicated to publishing clinical images from all sectors of medicine. The goal of this magazine is to disseminate information about new discoveries and treatments in science and medicine.

Quick Links

OTHER LINKS

Contact Us

Journal of Clinical & Medical Case Reports, Images , Frisco, Texas 75070, USA

support@jcmcrimages.org

+1 (231) 999-1496

Copyright ©2024 All rights reserved

TOP