Mediastinum
Nonneoplastic
Thymic dysplasia


Topic Completed: 1 December 2012

Minor changes: 20 November 2019

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PubMed Search: Thymic dysplasia

Hanni Gulwani, M.B.B.S.
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Cite this page: Gulwani H. Thymic dysplasia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/mediastinumthymicdysplasia.html. Accessed June 1st, 2020.
Definition / general
  • Congenital thymic alteration due to developmental arrest
  • Lack of differentiation of thymic epithelium, responsible for absence of Hassall corpuscles, is main feature (Histopathology 1992;21:499)
Clinical features
  • Associated with severe combined immunodeficiency syndrome, ataxia telangiectasia, chromosomal instability syndromes, Nezelof syndrome (Arch Pathol Lab Med 1987;111:1118)
  • Incomplete form of DiGeorge syndrome is congenital anomaly with a constellation of findings that includes thymic hypoplasia (J Cutan Pathol 2008;35:380); complete form has absent thymus
Gross description
  • Small thymus (< 5 g)
Microscopic (histologic) description
  • Tubules and rosettes of primitive appearing epithelium without segregation into cortical and medullary regions
  • No Hassall corpuscles, no / rare lymphocytes
Differential diagnosis
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