Thymic Hyperplasias in Practice: Clinical Context, Histological Clues, and Management Implications

Area of Science:

• Pathology
• Immunology
• Histology

Background:

• Thymic hyperplasias are a heterogeneous group of non-neoplastic thymic conditions.
• Distinguishing these entities is critical due to varied clinical associations and management implications.

Purpose of the Study:

• To review and synthesize current knowledge on distinct types of thymic hyperplasia.
• To delineate the histological diagnostic boundaries between true thymic hyperplasia, rebound thymic hyperplasia, thymic follicular hyperplasia, and lymphoepithelial sialadenitis-like thymic hyperplasia.

Main Methods:

• Systematic literature review of Medline database up to November 2025.
• Inclusion of studies on histopathological, radiological, and clinical presentations of thymic hyperplasias.
• Inclusion of reference works on age-related thymus size and weight.

Main Results:

• Thymic hyperplasias, while benign, exhibit diverse histological patterns and clinical scenarios.
• True and rebound thymic hyperplasia lack autoimmunity association but differ in age and context.
• Thymic follicular hyperplasia links to myasthenia gravis; lymphoepithelial sialadenitis-like hyperplasia associates with autoimmune diseases and lymphoma.

Conclusions:

• Clinical history, serology, imaging, and histopathology are essential for differentiating thymic hyperplasias.
• Some thymic hyperplasias require systemic evaluation due to links with autoimmune diseases or lymphomas.