Testis and epididymis
Paratesticular tumors
Adenomatoid tumor

Topic Completed: 1 February 2015

Revised: 28 March 2019

Copyright: 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Adenomatoid tumor [title] testis

Swapnil U. Rane, M.D.
Page views in 2018: 10,975
Page views in 2019 to date: 11,333
Cite this page: Rane S. Adenomatoid tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/testisepidadenomatoid.html. Accessed November 15th, 2019.
Definition / general
  • Benign tumor of mesothelial origin affecting testicular adnexa
  • Most commonly lower pole of epididymis; also tunica vaginalis, spermatic cord
Clinical features
  • Presents as solid, well circumscribed mass in scrotum, often associated with pain
  • Usually 1 - 5 cm, rarely larger (Cancer 1972;30:244)
  • Benign, even if it extends into testis
  • Suspected clinicoradiologically, confirmed histologically
  • No specific laboratory finding; however, negative markers for germ cell tumor are helpful in excluding a germ cell malignancy
Radiology description
  • Not specific
  • USG reveals a relatively hypo, iso to hyperechoic mass at lower pole of epididymis, not distorting the testis
Prognostic factors
  • Uniformly benign behavior, no reports of malignant transformation
Case reports
  • Complete excision
  • Frozen section examination may prevent unnecessary radical orchiectomy
Clinical images

Images hosted on other servers:

Solid mass at lower pole of right testis

MRI, lesion at lower right testis

Intratesticular 8 mm lesion

Gross description
  • 1 - 5 cm, well circumscribed solid tumor, adherent to testis / testicular adnexa
  • Cut surface may have small cystic spaces
Gross images

Images hosted on other servers:

Well encapsulated tumor

Firm, whitish gray, homogenous

Microscopic (histologic) description
  • No distinct growth pattern
  • Unencapsulated, cuboidal to flat cells forming cords that are either epithelial-like or form channels with dilated lumina simulating vessels
  • Cells have acidophilic cytoplasm with cytoplasmic vacuoles
  • Nuclei lack nucleoli
  • Mitoses and necrosis are usually absent
  • Intervening stroma may have smooth muscle and elastic fibers, desmoplastic quality and inflammatory cells
  • Rarely, tumor may extend into testicular parenchyma (Arch Ital Urol Androl 2014;86:44) or even rarer, be totally inside the testis (Eur Urol 1996;30:127, Indian J Urol 2009;25:126)
  • Patterns have been decribed (Cancer 1974;34:306, Am J Clin Pathol 1981;76:627) but most tumors show a mixture of:
    • Adenomatoid (tubular): glandular pattern with cytoplasmic vacuoles giving a signet ring appearance
    • Angiomatoid (canalicular): cells have a more endothelial appearance
    • Solid (plexiform): cells have a more epithelial appearance
    • Cystic (mixed): rare; tumor is in form of cystic spaces lined by cuboidal to flattened lining epithelium
Microscopic (histologic) images

Images hosted on other servers:

Low magnification

Intracytoplasmic vacuoles

Cytological features

Adenomatoid pattern

Lymphoid infiltrate

Dilated tubular structures

Various images

Tubules, cords and glandular arrangement



Cytology description
  • Smears are moderately cellular with sheets of monotonous round to oval cells showing indistinct cell borders and moderate to abundant pale cytoplasm with vacuolations
  • Nuclei are eccentric in location but regular with inconspicuous nucleoli
Cytology images

Images hosted on other servers:

Moderate cellularity

Monolayered sheets of cells

Positive stains
Negative stains
Electron microscopy description
  • Prominent microvilli, desmosomes and tonofilaments associated with dilated intercellular spaces
Molecular / cytogenetics description
  • No specific genetic abnormality has been identified
Differential diagnosis
Additional references
Back to top