Testis & paratestis

Nonneoplastic lesions


Last author update: 1 December 2012
Last staff update: 18 July 2023

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PubMed Search: Orchitis testis

Sean R. Williamson, M.D.
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Cite this page: Williamson S. Orchitis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testisorchitis.html. Accessed October 2nd, 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
Granulomatous orchitis
  • Rare; usually men 40 - 59 years with sudden onset of tender testicular mass, variable fever
  • May be a response to acid fast products of disintegrated sperm, postinfectious or due to trauma or sarcoidosis
  • Resembles pyogenic epididymo-orchitis
  • Benign, although granulomatous inflammation may be associated with seminoma
  • Recommend cultures to rule out infectious process (brucellosis, leprosy, sarcoidosis, syphilis, TB)
  • Granulomatous ischemic lesion
    • Usually affects head of epididymis
    • May be due to ischemia with secondary granulomatous reaction and scarring
  • Gross description
    • Solid, unilateral nodular enlargement of testis; resembles lymphoma
  • Microscopic (histologic) description
    • Lymphocytes and plasma cells infiltrate interstitium and surround seminiferous tubules
    • Giant cells and histiocytes that resemble (but are not) actual granulomas
    • Granulomatous ischemic lesion
      • Zone of necrosis involving efferent ducts and interstitial connective tissue, with adjacent lymphocytes and macrophages
      • Macrophages form large clusters with cholesterol crystals and foreign body type giant cells in duct lumen
      • Also intratubular epithelial regeneration and proliferation of small ducts showing epithelial regeneration and numerous spermatozoa in their lumen
      • Associated with ceroid granuloma, spermatic granuloma and epidermoid metaplasia of the efferent ducts
  • Reference: Am J Surg Pathol 1997;21:951
  • 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
    • 3 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
    • One - third 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
    • Usually begins in epididymis and spreads to testis
    • Prostate and seminal vesicles are usually also infected
    Gross images

    Contributed by Yale Rosen, M.D. and @SueEPig on Twitter

    TB orchitis

    Granulomatous orchitis

    Granulomatous orchitis

    Images hosted on other servers:


    Microscopic (histologic) images

    Contributed by Sean R. Williamson, M.D. and @SueEPig on Twitter

    Tuberculosis involving testis and paratestis

    Granulomatous orchitis Granulomatous orchitis Granulomatous orchitis

    Granulomatous orchitis

    Differential diagnosis
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