Vaginal adenosis

Vaginal adenosis is the presence of cervical or endometrial tissue inside the vaginal wall that is prone to unusual changes (metaplastic).

The presence of this tissue is understood to be derived from the remnants of the tissue that eventually turns into the fallopian tubes, uterus, and upper vagina, Müllerian ducting.

Vaginal adenosis has generally disappeared from literature, since the recall of an oestrogen drug given to women for a few decades as a miscarriage preventer. It may now occur in adult women without consequence.

Spontaneous vaginal adenosis particularly rare – about 10 per cent of adult women will be found with it – but in women exposed to diethylstilboestrol (DES) in the womb, the number rises to up to 90 per cent. That 90 per cent have a much higher risk of vaginal cancer.

How vaginal adenosis occurs in DES-affected women

The exact mechanism of how vaginal adenosis appears is not fully understood, but a working theory exists for DES-affected women. In the womb, the cervix and most of the vagina are lined with a specific cell, columnar epithelium.

At birth, most of these cells have converted to squamous epithelium. Further changes occur at puberty and onwards. DES administration may stop this conversion of cells, and allow columnar epithelium to remain in the vagina and outer portion of the cervix (the ectocervix).

As the delayed conversion occurs at puberty, these glandular structures are still present. This results in small ‘glands’ in the vaginal mucosa being covered by squamous epithelium, replacing the glandular tissue completely, eventually.

The presence of these glands, either covered or uncovered, is called adenosis. When the change in cells from columnar epithelium to malignant cells occurs is unknown, as is the delay of 10-30 years.

The effect seems to be dose-dependent: mothers whose daughters have adenosis or clear-cell cancer had greater exposure earlier in the pregnancy.

How vaginal adenosis occurs in non-DES-affected women

Vaginal adenosis appears to be related to hormone use, with the oral contraceptive pill or other hormonal birth control or therapies possibly playing a role.

References

Laronda MM, Unno K, Butler LM, Kurita T. The development of cervical and vaginal adenosis as a result of diethylstilbestrol exposure in utero. Differentiation. 2012;84(3):252-60.