Testis & paratestis


Testicular regression syndrome / anorchia

Last author update: 1 September 2012
Last staff update: 9 September 2020

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PubMed Search: Anorchia [title] OR testicular regression [title]

Turki Al-Hussain, M.D.
Sean R. Williamson, M.D.
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Cite this page: Al-Hussain T, Williamson S. Testicular regression syndrome / anorchia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testistesticularregression.html. Accessed September 25th, 2023.
Definition / general
  • Anorchism: absence of both testis
  • Monoorchidism: absence of one testis
  • Testicular regression syndrome: phenotypically normal male with vas deferens is present
  • Causes: cryptorchidism, possibly testicular infarct, infection, trauma, torsion or prenatal hormone induced atrophy due to overproduction of androgens
Testicular regression syndrome
  • Either no gonadal or testicular formation or regression of testicular tissue with residual fibrovascular nodule (mean 1.1 cm), calcification and hemosiderin
  • Rudimentary epididymis and spermatic cord are present
  • External genitalia depends on chronology of gonadal injury
Case reports
  • 1 year old boy with undescended testis and firm nodule near external inguinal opening (Case of the Week #279)
Microscopic (histologic) description
  • Regressed testis indicated by fibrosis, hemosiderin, calcification or Leydig cells near epididymis or proximal vas deferens (Arch Pathol Lab Med 2000;124:694)
  • Presence of only fat and connective tissue does not rule out an intraabdominal testis
Microscopic (histologic) images
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