benign and premalignant disease of cervix

BENIGN AND PREMALIGNANT CONDITIONS OF THE CERVIX:


Cervical anatomy and histopathology:
Transformation zone
The ectocervix is covered by squamous epithelium, a stratified epithelium very similar to skin, but lacking keratin. The canal of the cervix, is lined by columnar epithelium, only one cell thick, and the point where these two epithelia meet is called the squamocolumnar junction (SCJ)
the uterine cervix increases in size in response to oestrogens; and because the cervix is anchored at the vaginal fornices the end result of any enlargement is eversion of the cervix and exposure the columnar epithelium of the endocervical canal (the columnar epith is arranged into folds forming crypts and ridges). This occurs dramatically in the neonate under the influence of maternal oestrogens, at puberty under the influence of rising oestrogen levels, during the use of the combined oral contraceptive pill and during the first pregnancy and this is called ectopy (display of columnar epithelium) previously known as ‘erosion’.
In approximately 4% of women there will be extension of the squamocolumnar junction into the anterior and posterior fornices.
Macroscopically the columnar epithelium is red in color because of single cell layer allowing the blood vessels in the underlying stroma to be seen through it.

cervical metaplasia
Exposure of this columnar epithelium to low pH as found within the vagina promotes a series of physiological changes, known as squamous metaplasia, the metaplasia occurs at the transformation zone. The squamous epithelium is rich with glycogen.
Nabothian follicle:
Metaplasia usually occurs initially in the ridges of the mucous membrane folds and may well bridge over the crypts leaving a squamous cover with columnar epithelium remaining within the crypts, if a crypt cannot expel the mucus produced from the columnar epithelium a retention cyst or Nabothian follicle will occur. They are entirely benign and are not associated with infection, i.e they are not a sign of cervicitis.

ENDOCERVICAL POLYPS
The recognition of endocervical polyps at the time of taking a cervical smear is common and usually increases with age up to the menopause. Occasionally these polyps will be symptomatic producing heavy vaginal discharge or bleeding upon coital contact.
Histology of these polyps will show that they consist of columnar epithelium sometimes with metaplastic squamous epithelium across the tip. Malignant change is most unusual. However, if these polyps are removed by polypectomy, tissue should be sent for histology.
Because 15% of uterine tumours will be polypoidal and occasionally will extrude through the external cervical os.