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- The normal vagina is lined with squamous epithelium. Adenosis is characterized by the presence of columnar epithelium or glandular tissue in the wall of the vagina.
- At about the 15th week of embryologic development, the Müllerian system, which forms the upper 2/3 of the vagina, fuses with the invaginating cloaca or urogenital sinus to form the lower 1/3 of the vagina. Squamous metaplasia from the cloacal region then produces a squamous epithelium through the vagina.
- Adenosis occurs when this squamous epithelium fails to epithelialize the vagina completely.
- 3 main types of adenosis epithelium described:
- System(s) affected: Reproductive
- Adenosis is a disorder of the young female. By menopause, the vagina and cervix should be completely epithelialized.
- The presence of glandular epithelium in the postmenopausal patient is an indication for excision and close evaluation for the possibility of a well-differentiated adenocarcinoma.
Pregnancy produces a wide eversion of the transformation zone of the cervix. This occasionally will become so widely everted that it will extend onto the vaginal fornices, leading to the impression of adenosis. This will resolve after the pregnancy is completed.
- While the incidence of vaginal adenosis is unknown, the incidence of cloacal malformations is 1/20,000–1/25,000 live births.
- Predominant age:
- Teenage years: Epithelialization occurs from puberty to ~20 years of age.
- By age 30 years, it is extremely rare for adenosis to be present.
In the US: Adenosis is relatively common, affecting 10–20% of young females studied. As maturation progresses with puberty, epithelialization occurs (1).
Adenosis of the vagina/cervix in female offsprings is significantly higher in those exposed to diethylstilbestrol (DES) before birth (2).
None: Last DES exposure in the 1970s
- In most young females, the etiology is incomplete squamous metaplasia or epithelialization. This occurs as a natural phenomenon and resolves with age.
- Described as congenital or acquired (3):
- Congenital: Proliferation of the remnant Müllerian epithelium in the vagina due to exposure to DES in utero
- Acquired: Trauma and inflammation causing spontaneous de novo changes or changes in an acquired lesion in the vaginal epithelium:
- Trauma: Carbon dioxide laser, 5-fluorouracil, vaginal packs, chronic pessary use
- Proliferation of the glandular cells in the remnant Müllerian epithelium of the vagina due to sex hormones
- Idiopathic spontaneous change in epithelium; no cause has been identified
In DES-exposed females, the incidence of adenosis is higher; the etiology presumably is from the effect of the DES on the developing embryologic system.
Commonly Associated Conditions
- Adenosis from DES exposure should lead to an evaluation of other DES-related abnormalities.
- Müllerian tract anomalies associated with DES exposure include cervical hood, cervical ridge, shortened cervix, incompetent cervix, and T-shaped uterine cavity.
- Patients with known DES exposure should have their reproductive tract evaluated prior to conception.
- Most patients with adenosis have not been DES exposed and do not require evaluation of the reproductive system.
- DES was last used to prevent spontaneous abortion in the US in 1971; therefore, it is decreasing in clinical significance.