Testis and epididymis
Nonneoplastic lesions
Hernia sac with mesothelial entrapment

Author: Jason Tretter
Editor-in-Chief: Debra Zynger, M.D.
Jason Tretter

Topic Completed: 1 June 2018

Revised: 5 April 2019

Copyright: 2003-2018, PathologyOutlines.com, Inc.

PubMed Search: hernia entrapment pathology

Jason Tretter
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Page views in 2019 to date: 3,124
Cite this page: Tretter J. Hernia sac with mesothelial entrapment. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/testisherniasacepid.html. Accessed October 16th, 2019.
Definition / general
  • Entrapment of mesothelial cells within hernia sac fibroadipose tissue
Essential features
  • Persistent serosal injury causes reactive hyperplasia of the mesothelial lining and submesothelial fibrosis, entrapping mesothelial cells beneath the mesothelial lined surface (Mod Pathol 2005;18:S131, Diagn Pathol 2011;6:78)
Clinical features
  • Similar clinical presentation as a patient with a hernia sac without mesothelial entrapment (usually hydrocele, also hematocele, cyst adjacent to epididymis, hemorrhagic epididymal cyst, pyocele) (Am J Surg Pathol 2014;38:54)
Prognostic factors
  • Similar treatment as a hernia without mesothelial entrapment, i.e. excision of hernia sac (J Urol 2011;186:1620)
Gross description
Microscopic (histologic) description
Microscopic (histologic) images

Images hosted on PathOut server:

Contributed by Debra L. Zynger, M.D.

Low power

Cords, glands and small nests

Gland formation

Entrapped mesothelium



Negative stains
Molecular / cytogenetics description
Differential diagnosis
Board review question #1
    Which of the following is a feature of a hernia sac with mesothelial entrapment?

  1. Glands parallel to surface
  2. GLUT-1 and p53 positivity
  3. Homozygous for 9p21 deletion
  4. Invasion into muscle
  5. Prominent mitotic activity
Board review answer #1
A. Glands parallel to surface
Board review question #2

    A 48 year old man presents with a hydrocele with the findings in the above picture. What is your diagnosis?

  1. Adenomatoid tumor
  2. Diffuse malignant mesothelioma
  3. Hernia sac with mesothelial entrapment
  4. Histiocytic inflammation
  5. Metastatic adenocarcinoma
Board review answer #2
C. Hernia sac with mesothelial entrapment
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