Mixed epithelial and mesenchymal tumors

Topic Completed: 1 March 2017

Minor changes: 5 August 2020

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PubMed search: adenofibroma uterus

Özlem Isiksacan Özen, M.D.
Ayse Ayhan, M.D., Ph.D.
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Cite this page: Özen Ö. Adenofibroma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/uterusadenofibroma.html. Accessed September 30th, 2020.
Definition / general
Essential features
  • First described by Ober in 1959 as a benign form of mixed mesodermal tumor (Ann N Y Acad Sci 1959;75:568) and detailed in 1973 (Am J Clin Pathol 1973;60:543)
  • Diagnosis has been historically reserved for polyps composed of glands set in fibromatous mitotically inactive stroma, and unqualified diagnosis is discouraged (Soslow: Uterine Pathology, 1st ed, 2012)
    • Zones of histological overlap in adenofibroma-adenosarcoma spectrum
    • Classification should be based on the histologically MOST MALIGNANT area
    • Most (ALL, by some authorities) of these tumors fall within the spectrum of low grade sarcoma
    • However, if they exist, they are clinically benign
  • Necessitates thorough sampling for correct diagnosis
  • If still problematic after repeat sampling, evaluate imaging studies especially when fertility preservation is necessary
  • May be extremely difficult to distinguish from low grade adenosarcoma (Am J Surg Pathol 2009;33:278)
  • Synonyms: Müllerian adenofibroma, papillary adenofibroma
ICD coding
  • 9013/0
  • In uterus, mostly endometrial - may also rarely be in endocervical, ovarian, pelvic ligaments
  • Subjective niche between endometrial polyps on one hand and the low end of the spectrum of adenosarcoma on the other
  • Origin is a continued source of debate; may be related to: papillary adenofibroma, cystadenofibroma, lipoadenofibroma and adenomyosis
  • Occasional cases have been associated with tamoxifen therapy (Int J Clin Exp Pathol 2015;8:15381, J Med Ultrason 2005;32:71, Abdom Imaging 2002;27:592)
  • Some authors believe that (at least) some of the tumors currently classified as adenofibromas (on the basis of their low mitotic count and lack of significant nuclear atypia) are well differentiated adenosarcomas, they recommend classifying as adenosarcoma of low malignant potential (Am J Surg Pathol 2009;33:278)
Clinical features
  • Only by histopathology - thorough microscopic examination
Prognostic factors
Case reports
Gross description
  • Similar to those of adenosarcoma: polypoid masses within the endometrial cavity
  • May involve lower uterine segment or cervix with similar macroscopy at mucosa
  • Rarely mural or serosal
  • Usually solid but a minor cystic component may be seen
  • Otherwise polypoid, broad based; firm, papillary without necrosis
  • Reference: WHO Classification of Tumours of the Female Reproductive Organs, 4th ed, 2014
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Ayse Ayhan, M.D., Ph.D. and Özlem Özen, M.D.

Top: left side is adenofibroma,
right side is endometriosis
Bottom: magnified endometriosis

Periglandular cuffing is not
prominent, no cleft formation,
no atypia nor mitotic activity,
suggests adenofibroma

Foci of adenofibroma-like growth

Focus of adenofibroma-like growth
(stromal alterations are disturbing)

Focal atypia

Periglandular condensation

Diagnosis: adenosarcoma, based on
periglandular cuffing, atypia and mitoses

Images hosted on other servers:

Various images

Dense fibrous
connective tissue and
glandular spaces

Differential diagnosis
Board review style question #1

  1. Can be diagnosed in curettings or biopsy materials.
  2. Contains rare mitotic figures (< 2 MF/10 HPF).
  3. Is a benign pure mesodermal tumor composed of endometrial stromal or fibroblastic cells.
  4. Requires immunohistochemistry for diagnosis.
  5. Typically shows periglandular stromal condensation and mild stromal cell atypia.
Board review answer #1
B. Contains rare mitotic figures < 2 MF/10 HPF.

Adenofibroma is a benign form of mixed mesodermal tumor composed of an admixture of Müllerian epithelium and stroma, both components being benign. It should be diagnosed only in a well sampled tumour removed totally and thorough microscopic examination is needed since the diagnosis can be made only by histopathology. The tumor is typically characterized by showing no periglandular stromal condensation and no stromal cell atypia with < 2 MF/10 HPF.
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