Testis & paratestis

Mesothelial tumors

Well differentiated papillary mesothelial tumor

Editor-in-Chief: Debra L. Zynger, M.D.
Jennifer Gordetsky, M.D.

Last author update: 1 November 2013
Last staff update: 20 October 2022

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PubMed Search: Well differentiated papillary mesothelial tumor

Related topics: Malignant mesothelioma

Jennifer Gordetsky, M.D.
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Cite this page: Gordetsky J. Well differentiated papillary mesothelial tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/testismesothelioma.html. Accessed June 2nd, 2023.
Definition / general
  • Histologic variant of mesothelioma composed entirely of bland papillary structures and tubules with no identifiable invasion
  • Usually occurs in the peritoneum of young women
  • Few cases reported in the tunica vaginalis of the testis
  • Ages ranging from 18 to 69
  • Peritoneum and tunica vaginalis
Clinical features
  • Scrotal / peritesticular mass, associated with hydrocele
  • Mesothelial origin can be confirmed by immunohistochemical stains
Case reports
Radiology images

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Scrotal ultrasound

  • Complete excision
Microscopic (histologic) images

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Typical tubulopapillary pattern

Psammoma body in papillary area

Bland papillary structures

Cytology description
  • Moderately cellular, uniform epithelioid cells arranged in papillary groups with fibrovascular cores
  • Cells have moderate cytoplasm, uniform round nuclei, distinct nucleoli
  • Minimal atypia
  • Few lymphocytes scattered in the background
  • No mitoses
Positive stains
Negative stains
  • p53 (may have focal positivity), CEA
Electron microscopy description
  • Tumor cells are round to polygonal in shape with numerous short and long slender microvilli on the free surfaces
  • Cytoplasmic organelles include moderate amounts of mitochondria, moderate amounts of rough endoplasmic reticulum, free ribosomes and microfilaments
  • Centrally located oval nuclei, euchromatin and prominent nucleoli
  • Well developed desmosomes (Pathol Res Pract 2010;206:105)
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