What are the histologic findings in Klinefelter syndrome?

Updated: Mar 23, 2020
  • Author: Germaine L Defendi, MD, MS, FAAP; Chief Editor: Luis O Rohena, MD, MS, FAAP, FACMG  more...
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In prepubertal boys with Klinefelter syndrome, testicular biopsies may reveal preservation of seminiferous tubules with reduced numbers of germ cells; Sertoli and Leydig cells appear normal. [43]

Testicular biopsies of adult males with Klinefelter syndrome are characterized by extensive fibrosis and hyalinization of the seminiferous tubules and hyperplasia of the interstitium; however, the tubules may show residual foci of spermatogenesis. Histologic findings may include small, firm testes with seminiferous tubular hyalinization; sclerosis; and atrophy with focal hyperplasia of mostly degenerated Leydig cells. Germ cells are markedly deficient or absent. [43]

In Klinefelter syndrome males with mosaicism, a progressive degeneration and hyalinization of seminiferous tubules occurs following puberty, despite the presence of normal-sized testes and spermatogenesis at puberty.

Histology of gynecomastic breasts reveals hyperplasia of interductal tissue.

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