Testis & paratestis

Nonneoplastic lesions

Infectious orchitis

Last author update: 1 December 2012
Last staff update: 10 September 2020

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PubMed Search: Infectious testicular lesions

Sean R. Williamson, M.D.
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Cite this page: Williamson S. Infectious orchitis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testisinfectious.html. Accessed March 22nd, 2023.
  • Associated with markedly reduced spermatogenesis, arrested maturation, germ cell aplasia, tubular hyalinization / thickening of basement membranes, interstitial inflammation and fibrosis, reduction in Leydig cells, Sertoli cell only pattern (J Pathol 1991;163:47, Urology 1999;53:203, Mod Pathol 1989;2:233, Hum Pathol 1989;20:210)
  • Often other infections in testis or epididymis (Candida, CMV, Histoplasma, mycobacteria, toxoplasmosis)
  • Testicular atrophy related findings do not appear to be immune mediated (Hum Pathol 1989;20:572)
  • Testis is an uncommon location for Kaposi sarcoma in AIDS patients
  • Zoonotic infection acquired from sheep, camels, cattle, dogs, goats, reindeer, swine via skin / mucous membrane contact or contaminated animal products
  • Affects testis and epididymis (epididymo-orchitis) in 2 - 20% of cases, causing scrotal pain, swelling, fever
  • Often diagnosed by laboratory studies
  • Case report: 32 year old man with painless testicular mass-brucellosis (Int J Urol 2004;11:683)
  • Micro description: granulomatous or testicular abscess
  • Treatment: antibiotics; orchiectomy if resembles a neoplasm or refractory to therapy
  • Additional references: Urol Int 2009;82:158, BMC Res Notes 2011;4:286, Clin Infect Dis 2001;33:2017
  • Usually spreads from posterior urethra to prostate, seminal vesicles and epididymis
  • Testis involved only if untreated
Histoplasma capsulatum
  • Rarely presents as testicular mass
  • May resemble sperm granuloma (J Clin Pathol 1974;27:929)
  • Caseating granulomatous inflammation with giant cells
  • Small yeast forms (2 - 5 micrometers) are identifiable by silver stain (J Urol 2000;164:1652)
  • Does not occur in U.S.
  • Rarely presents with orchitis (Am J Clin Pathol 1980;73:712)
  • Testicular involvement thought to be facilitated by lower temperature of scrotum
  • Three phases of testicular involvement:
    1. Vascular phase: blood vessels show perivascular lymphocytic inflammation and interstitium is filled with macrophages containing mycobacteria
    2. Interstitial phase: endarteritis, Leydig cell clusters, interstitial fibrosis, histiocytes containing acid fast bacteria and reduced spermatogenesis
    3. Obliterative phase: dense fibrosis, no detectable tubules, reduced vessels, rare acid fast bacteria; associated with gynecomastia and infertility
  • Testicular infections rare in infected children (prepubertal) but occur in 15 - 40% of postpubertal men one week after parotiditis
  • Usually unilateral (bilateral in 15 - 30%); epididymitis is also common (85%) and often precedes orchitis
  • 1/3 of infected postpubertal men develop testicular atrophy, 2 - 10% become infertile
  • Incidence increasing, due to reduced use of vaccine (BJU Int 2010;105:1060)
Pyogenic epididymo-orchitis
  • Usually due to E. coli
  • Resembles granulomatous orchitis
  • Complications: venous thrombosis, septic testicular infarct
  • Testis usually involved first
  • Discrete gummas contribute to enlarged, irregular testis
  • Gummas: diffuse interstitial inflammation with edema, lymphocytes and plasma cells, with obliterative endarteritis and perivascular cuffing
  • Spirochetes usually identified in gummatous but not fibromatous stages
  • Tuberculosis
    • Usually begins in epididymis and spreads to testis
    • Prostate and seminal vesicles are usually also infected
    Gross images

    Contributed by Yale Rosen, M.D.

    TB orchitis

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    Microscopic (histologic) images

    Contributed by Sean R. Williamson, M.D.

    Tuberculosis involving testis and paratestis

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