Testis & paratestis

Nonneoplastic lesions

Hydrocele


Resident / Fellow Advisory Board: Alcino Pires Gama, M.D.
Deputy Editor-in-Chief: Maria Tretiakova, M.D., Ph.D.
Francesca Sanguedolce, M.D., Ph.D.

Last author update: 30 March 2023
Last staff update: 30 March 2023

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PubMed Search: Hydrocele

Francesca Sanguedolce, M.D., Ph.D.
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Cite this page: Sanguedolce F. Hydrocele. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testishydrocele.html. Accessed February 23rd, 2024.
Definition / general
  • Accumulation of serous fluid between visceral and parietal layers of tunica vaginalis
Essential features
  • Accumulation of serous fluid between visceral and parietal layers of tunica vaginalis
  • Idiopathic or associated with nonneoplastic or neoplastic lesions
  • Note: thorough macroscopic examination and extensive sampling are needed to rule out mesothelioma (Singapore Med J 2015;56:e53)
ICD coding
  • ICD-10: N43.3 - hydrocele, unspecified
  • ICD-11: GB00 - hydrocele or spermatocele
Epidemiology
Sites
  • Scrotum
  • Rarely, the hydrocele sac may extend beyond the scrotum to the abdomen via the inguinal canal (abdominoscrotal hydrocele) (Urol Case Rep 2020;32:101254)
Pathophysiology

Encysted variant
Funicular variant
Persistent communication
with the peritoneal cavity
No Yes
Etiology Defective closure at both
proximal and distal ends of
processus vaginalis
Defective closure of the distal
end of tunica vaginalis
Macroscopic differential
diagnosis
Inguinal lymphadenopathy,
hernia, tumor of the
spermatic cord
Reference: Acta Radiol 2007;48:1138
Etiology
  • Mostly idiopathic, putative causes: excessive secretion or decreased reabsorption of fluid by parietal mesothelial cells, congenital lack of efferent lymphatics
  • Association with inguinal hernia, scrotal trauma, inflammation (epididymoorchitis) or tumors of the testis / paratestis (BJU Int 2011;107:1852)
  • Filarial hydrocele (StatPearls: Filarial Hydrocele [Accessed 2 February 2023]):
    • Late and chronic manifestation of filariasis
    • Very common in endemic areas (tropical and subtropical countries)
    • Due to parasite induced blockage and dysfunction of the lymphatic vessels
Clinical features
Diagnosis
  • Usually diagnosed by physical examination and transillumination
Radiology description
  • Simple fluid collection at ultrasound; may contain septations, calcifications or cholesterol (Radiographics 2009;29:2017)
  • Avascular at Doppler evaluation
  • MRI: low signal on T1, high signal on T2 weighted images
Radiology images

Images hosted on other servers:

Scrotal MRI: cystic lesion

Encysted hydrocele

Case reports
Treatment
Gross images

Images hosted on other servers:

Abdominoscrotal hydrocele

Microscopic (histologic) description
  • Loose connective tissue lined by a single layer of cuboidal or flattened mesothelial cells
  • Lining may show mesothelial hyperplasia (both solid and papillary), squamous metaplasia or prominent atypia
  • Usually clear luminal fluid
  • Fibrinous exudate, chronic inflammatory infiltrate and fibrosis in longstanding cases, due to infection or hemorrhage (Cheng: Urologic Surgical Pathology, 4th Edition, 2019)
  • Occasional presence of florid nodular collections of histiocytes and aggregates of incidental benign small blue cells of possible rete epithelial origin (Hum Pathol 2010;41:88, Am J Surg Pathol 2016;40:1507)
Microscopic (histologic) images

Contributed by Francesca Sanguedolce, M.D., Ph.D.
Connective tissue, mild inflammation

Connective tissue, mild inflammation

Fibrosis, moderate inflammation

Fibrosis, moderate inflammation

Mesothelial lining

Mesothelial lining

Calretinin

Calretinin

Sample pathology report
  • Left testis, hydrocelectomy:
    • Hydrocele
Differential diagnosis
  • Testis tumor:
    • Solid mass at transillumination
  • Mesothelioma:
  • Spermatocele:
    • Cystic dilatation of the epididymis, efferent ductule or proximal rete testis
    • Negative for mesothelial markers
    • Spermatozoa and proteinaceous fluid in the lumen
    • Often ciliated epithelial lining
Board review style question #1

Which cell type lines a hydrocele?

  1. Endothelial cells
  2. Germinal cells
  3. Mesothelial cells
  4. Urothelial cells
Board review style answer #1
C. Mesothelial cells. Since hydrocele is defined as an accumulation of serous fluid between visceral and parietal layers of tunica vaginalis, its lining is provided by mesothelial cells.

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Reference: Hydrocele
Board review style question #2
Which microscopic findings can occur in a hydrocele?

  1. Acute inflammation, mucinous metaplasia
  2. Chronic inflammation, fibrosis, squamous metaplasia
  3. Clear cell hyperplasia
  4. Psammoma bodies
Board review style answer #2
B. Chronic inflammation, fibrosis, squamous metaplasia. Longstanding hydrocele may be complicated by inflammation and hemorrhage, resulting in abnormal findings involving both the lining cells and the connective tissue.

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Reference: Hydrocele
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