Adenomyosis / adenomyoma

Editorial Board Member: Ayse Ayhan, M.D., Ph.D.
Irem Onur, M.D.

Topic Completed: 1 October 2016

Minor changes: 5 August 2021

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PubMed Search: Uterine adenomyosis

Irem Onur, M.D.
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Cite this page: Onur I. Adenomyosis / adenomyoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/uterusadenomyosis.html. Accessed January 21st, 2022.
Definition / general
  • A nonneoplastic lesion of myometrial tissue characterized by the presence of endometrial glands and stroma within myometrium (Best Pract Res Clin Obstet Gynaecol 2006;20:511)
  • Synonyms: myometrial endometriosis, superficial adenomyosis (1 - 2.5 mm in myometrium), stromal adenomyosis, incomplete adenomyosis, adenomyosis with sparse glands
  • Usually an incidental finding in hysterectomy specimens (Int J Gynecol Pathol 1996;15:217)
  • May be diffuse or focal
  • May be involved by hyperplasia and carcinoma
  • Adenomyoma: A circumscribed nodular aggregate of benign endometrial glands surrounded by endometrial stroma, with leiomyomatous smooth muscle bordering the endometrial stromal component
ICD coding
  • ICD-10: N80.0 - endometriosis of uterus
  • Frequently in posterior, less commonly in anterior uterine wall
  • Rarely in cornua or by cervical os
  • Adenomyosis and endometriosis are usually regarded as closely related, but
    • Microscopic appearance, and probably their pathogenesis, are somewhat different
    • They may occur independently of each other
    • Adenomyosis mostly is made up of nonfunctional (basal) endometrium and is frequently connected with the mucosa (vs. endometriosis, composed of functional layers)
    • Adenomyosis may represents a unique form of endometrial diverticulosis
  • Hypothetical mechanisms include (Crum: Diagnostic Gynecologic and Obstetric Pathology, 2nd Edition, 2011)
    • Instillation of endometrium within the myometrium
    • In situ metaplasia of pluripotent stem cells retained in myometrium or
    • Improper partitioning of the endometrium from the myometrium
  • Of note, del(7) (q21.2q31.2), a deletion found in typical leiomyoma, has been found in three cases of adenomyosis, suggesting some pathobiologic overlap between leiomyomata and adenomyosis (Cancer Genet Cytogenet 1995;80:118)
  • Definitive distinction between these explanations requires further study
Clinical features
  • By histopathologic examination of well oriented hysterectomies
  • Essentially should not be diagnosed in curettings or hysteroscopic material
Radiology description
Prognostic factors
  • Benign; excellent prognosis even if not removed
Case reports
Gross description
Gross images

Contributed by Ayse Ayhan, M.D., Ph.D.
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Thickened and spongy myometrium

Microscopic (histologic) description
Microscopic (histologic) images

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

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Endometrial glands and stroma

Positive stains
Differential diagnosis
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