Other tumors

Adenomatoid tumor

Last author update: 1 October 2016
Last staff update: 3 March 2023 (update in progress)

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PubMed search: adenomatoid tumor uterus

Laura Ardighieri, M.D.
Ayse Ayhan, M.D., Ph.D.
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Cite this page: Ardighieri L. Adenomatoid tumor. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusadenomatoid.html. Accessed March 23rd, 2023.
Definition / general
  • Benign tumor of mesothelial origin
Essential features
  • Synonyms: benign mesothelioma, benign mesothelial tumor, benign adenomatoid mesothelioma
ICD coding
  • 9054 / 0
  • Reproductive aged women, mean 45 years, range 24 - 72 years
  • Sites
    • Neoplastic rather than reactive (based on molecular, clinical and pathological features)
    Clinical features
    • By histopathology
    • Routine hematological and biochemical parameters are within normal limits
    • Occasional anemia and low hemoglobin level because of uterine bleeding
    Radiology description
    • Magnetic resonance: small solid uterine masses with homogeneous hypointensity on T2 weighted images, and lower enhancement or cystic lesions with inner irregular solid nodules (J Comput Assist Tomogr 2015;39:499)
    Prognostic factors
    • Benign tumor with excellent prognosis
    Case reports
    • Surgical removal (hysterectomy or rarely simple excision)
    Gross description
    • Solitary, small (range 0.2 - 3.5 cm, average 2.1 cm), solid nodular, well circumscribed but non encaspulated, ill defined margins, grey - white - yellow rubbery cut surface
    • Occasionally grossly inconspicuous
    • Rarely diffuse, multifocal, large or predominantly cystic (J Cancer Res Ther 2015;11:967)
    • Large multicystic tumors have a honeycomb, spongy pattern / cysts filled with serous fluid
    • Exophytic serosal component may rarely be seen
    Microscopic (histologic) description
    • Organized in vascular-like, gland-like, complex slit-like and cystic branching spaces; also tubules or combination of above
    • Less commonly cribriform, solid, anastomosing cords, single cells, focal papillary architecture
    • Tubules may contain basophilic secretions
    • “Thread like bridging strands” (attenuated cytoplasm that traverse the pseudovascular spaces) (Ann Diagn Pathol 2003;7:273)
    • No mitoses; no necrosis; no atypia
    • Background: hyperplastic smooth muscle
    • Stroma: edematous, inflammatory infiltrate; sometimes lymphoid follicles; lymphocytes or foamy macrophages can be found in the lumina of the tubules
    Microscopic (histologic) images

    Contributed by Ayse Ayhan, M.D., Ph.D

    Various images

    Cytology description
    • Flattened, cuboidal epithelioid cells: scant, pale, eosinophilic cytoplasm (may contain vacuoles) with hairy basophilic apical surface
    • Bland, round nuclei, small nucleoli
    • Occasional signet ring-like cells, which are PAS-, mucicarmine-, and may be acidic Alcian Blue+ and colloidal iron+
    • No mitotic activity / no cytological atypia
    • Occasional nests of squamoid cells
    Electron microscopy description
    • Abundant long slender microvilli, desmosomes, complex intercellular canalicular system, single layer basement membrane (Cancer 1970;25:171)
    Molecular / cytogenetics description
    • Uniform non random pattern of X chromosome inactivation, consistent with monoclonality (Hum Pathol 2016;48:88)
    Differential diagnosis
    Additional references
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