Chronic Massive Left Hydrocele Sac

Karien Treurnicht, M.D.

Specimen Type:



A 47 year old man presented with a longstanding, large left hydrocele sac which was excised. Representative sections were taken from a fibrous piece of tissue, 6.0 x 7.0 x 0.5 cms.

Pathologic Features:

Sections show epididymis and an adjacent cyst with a fibro-muscular wall (Figure 1). There is moderate chronic inflammation of both the epididymis and the cyst wall (Figure 2). The lining of the cyst is mostly denuded, but where present, consists of a single layer of cuboidal epithelium with reactive changes and nucleolation (Figure 3). On closer inspection there are nests and ribbons of similar cells within the wall of the cyst in an apparent “layered” arrangement (Figures 4, 5 and 5). No necrosis, atypia or mitotic activity is seen.

Differential Diagnosis:

  • Benign cyst (hydrocele/spermatocele/mesothelial cyst) with reactive changes to longstanding inflammation and repair
  • Benign mesothelioma of the tunica
  • Adenomatoid tumour
  • Malignant mesothelioma of the tunica

What to call the cyst? The wall of the cyst includes definite prominent smooth muscle and is directly adjacent to the epidiydmis and although no spermatozoa are identified this is most in keeping with a spermatocele.

Benign papillary mesothelioma of the tunica: This entity is usually found in young men and there is an exophytic papillary component with psammoma bodies, which were not found in this case.

Adenomatoid tumour: These are found in the tunica vaginalis and epididymis in this age group and can be incidental findings. In this case there is no circumscribed mass as you would expect in an adenomatoid tumour, the tubules and nests are dispersed and there is no prominent vacuolation of the cells.

Malignant mesothelioma of the tunica: In epithelial variants of this highly aggressive tumour in the tunica nests of flattened mesothelial cells can be present, but an infiltrative growth pattern, atypia and mitoses are required, which were not present in this case.


Benign mesothelial entrapment in a spermatocele.

  • Incidental finding in a longstanding lesion which was clinically felt to be a hydrocele
  • “Layered” arrangement of cells and nests with fibrin on the surface, giving the impression of an injury and repair process in a background of significant ongoing chronic inflammation
  • Cells within the fibrous wall similar to those on the surface, including the degree of nucleolation and “reactive” appearances. No atypia, necrosis of mitoses seen
  • No surface exophytic component or psammoma bodies identified


  1. Bostwick DG, Cheng L. Urologic Surgical Pathology. Spermatic cord and testicular adnexae. Second Edition, Mosby, 2008; p869-883.