At the gynecology clinic, 28-year-old Luciana comes in because she was told that her Pap smear showed abnormal cervical cells. She is totally asymptomatic and her previous pap smear from 3 years ago was normal.
Next, there is 36-year-old Cassie who presents to the office after noticing vaginal bleeding after sexual intercourse. There’s no associated pain with urinating, bloody urine, constipation or pelvic pain. She admits she has never done a pap test in her life. Pelvic exam shows a friable mass growing on the cervix.
In further history, both have been sexually active with multiple sexual partners and use oral contraceptive pills as their method of contraception. Both Luciana and Cassie have different types of cervical pathologies.
So, first let’s talk physiology real quick!. The cervical canal can be divided into two sections. The endocervix is closer to the uterus, and is lined by columnar epithelial cells. The ectocervix is continuous with the vagina and it’s lined by mature squamous epithelial cells. Where the squamous epithelium of the ectocervix and the columnar epithelium of the endocervix meet, there’s a line called the squamocolumnar junction. For your exams, it’s necessary to remember that, right where the two types of cells meet, there’s the transformation zone, which is where cells multiply and transform into immature squamous epithelium through a process called metaplasia.
Now, metaplasia is when a stimulus, usually a stressor, causes the stem cells in a region to differentiate into another type of cell that replaces the typical cell type in that region. For example with Barrett’s esophagus, chronic stomach acid irritation causes the normal stratified squamous cells that line the esophagus to get replaced by simple columnar cells. This is different from dysplasia where fully differentiated cells turn into immature cells that have varying shape and nuclear morphology. Metaplasia is usually reversible if the stressor is removed while only mild or moderate dysplasia is reversible. So, in the cervix, right at the basal layer of the transformation zone is where dysplasia might start. This is also known as cervical intraepithelial neoplasia or squamous epithelial lesion.