Pleura & peritoneum


Adenomatoid tumor

Last author update: 1 February 2016
Last staff update: 24 December 2022

Copyright: 2003-2023,, Inc.

PubMed Search: Adenomatoid tumor [title] ovary

Joseph Peevey, M.D.
Rouba Ali-Fehmi, M.D.
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Cite this page: Peevy J, Abdulfatah E, Ali-Fehmi R, Bandyopadhyay S, Shi DP. Adenomatoid tumor. website. Accessed March 22nd, 2023.
Definition / general
  • Benign lesion, often incidental finding on oophorectomy specimen
  • More frequently these lesion are found in males (epididymis, spermatic cord and testicular membrane); however, in females lesions are seen more commonly in fallopian tubes, broad ligament and uterus
  • Thought to arise from mesothelial serosal cells
  • First described by Golden and Ash in 1945 (Am J Pathol 1945;21:63)
Essential features
  • Rarely found within ovary
  • Typically small with 0.5 - 3 cm incidental lesions near hilum
  • Previously known as benign mesothelioma of the genital tract
  • Ovarian and juxtaovarian sites are rare
  • Occur predominantly at the ovarian hilum and may extend into and replace the ovarian parenchyma
  • Most frequently unilateral, found within fallopian tube, broad ligament or on uterine serosal surface
Pathophysiology / etiology
Clinical features
  • Asymptomatic, discovered as an incidental finding
  • Usually 0.5 - 3.0 cm, rarely larger and symptomatic
  • Histologic recognition, confirmed by immunophenotype
  • Often incidental
Radiology description
  • Not routinely performed for primary diagnosis
  • Case reports describe incidental lesions on transvaginal ultrasound displaying multilocular cystic mass often with vascularized central / solid portion
  • Radiographic differential diagnosis, if provided, may include epithelial tumors, inclusion peritoneal cysts, and multiple large follicles
  • CT imaging seldom describes lesion (J Clin Ultrasound 2005;33:233)
Prognostic factors
  • Benign behavior, no reports of recurrence or malignant transformation
Case reports
  • Excision results in complete cure
  • Recurrence after excision is rare
Gross description
  • Small, round to oval, well circumscribed tumor
  • Cut surface may have small cystic spaces
Microscopic (histologic) description
  • Composed of clefts and spaces lined by cuboidal, low columnar or flattened epithelial-like cells
  • Surrounded by connective tissue that varies from loose and edematous to dense and hyalinized
  • The epithelial-like cells may exhibit marked vacoulation, which in some cases may contain weakly basophilic material
  • A spotty lymphoid aggregate may be a low power clue to the diagnosis
  • Distinctive thread-like bridging strands crossing the tubular spaces are useful diagnostic features
  • Morphologic patterns:
    • Adenoid
    • Angiomatoid
    • Cystic
    • Glandular
    • Solid
    • Tubular
    • Plexiform
    • Canalicular
  • Similar appearance to appearance found within other locations
  • Relatively well demarcated, nonencapsulated solid aggregates of cells forming cleft-like spaces lined by low columnar to cuboidal flattened epithelial-like cells
  • Cells often surrounded by stroma that ranges from dense / fibrotic to loose / edematous
  • Epithelial-like cells may display marked vacuolization, signet ring cell-like appearance or oxyphilic cytoplasm
Microscopic (histologic) images

AFIP images
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Scattered cysts

Contributed by Eman Abdulfatah, M.D.
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Adenoid pattern, 40x

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Adenoid pattern, 100x

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Angiomatoid pattern, 40x

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Angiomatoid pattern, 100x

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Trabecular pattern, 40x

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Trabecular pattern, 100x

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
Positive stains
Negative stains
Electron microscopy description
  • No microvilli, no bundles of cytoplasmic filaments, no tight junctional complexes, no intercellular spaces
Molecular / cytogenetics description
  • No specific genetic abnormality has been identified
Differential diagnosis
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