Cervical intraepithelial neoplasia – CIN

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Your last PAP test was reported as CIN 1, CIN 2, CIN 3 or simply as a POSITIVE PAP TEST? What do these changes mean and how can they reflect on your health?


Two steps are necessary in order to make a PAP test. In the first step, the gynecologist takes cells from the surface of the cervix by gently scratching, using a wooden spatula or a special brush. In the second step, these cells are being put on a glass and fixated with a special chemical. The fixated cells are taken to a Papanicolau staining in the departments of Pathology. In the end, the pathologists look at the stained cells under a microscope, evaluate them and send the result back to the gynecologist who then announces it to the patient.

NEGATIVE PAP TEST means that no changes were detected in the cervical cells and they are considered healthy. These patients should make another PAP test after 12 months.

POSITIVE PAP TEST means that certain changes were seen in the cervical cells. But, before you start with a treatment, you should go through another process which will confirm those changes.  This is because the PAP test is only a screening method, i.e. a fast method to check the health of the cervical cells.  The next procedure makes a detailed examination of the cervix using a type of a microscope and finding the exact spot which made the PAP test positive and taking a biopsy from that place (a small part of the tissue). The biopsy is taken to the pathologists. After we receive the results, we will know whether the PAP test was confirmed or negated, and up until we receive the results it is just an assumption and shouldn’t be considered a definitive diagnosis. The diagnosis is set solely on the basis of histological preparations obtained by colposcopic biopsy from the affected area, and not on the PAP test.

POSITIVE PAP TEST means that the pathologist who reported the PAP test saw cellular changes in the cells from the surface of the cervix. These cellular changes are described in one way, but are classified in different ways since the introduction of the PAP test in 1943. In some ways, this causes confusion in the understanding of the PAP findings. In the beginning, 1943 – 1970, the cellular changes were classified as changes in the first group, changes in the second group, and so on until changes in the fifth group. This classification went through some changes in the 60s, and since 1970, the cellular changes have a new classification: CIN 1, CIN 2 and CIN 3. This classification was changed in 1991, and since then the terms LSIL and HSIL are used, i.e. the cellular changes are described based on their potential to turn in cancer cells. LSIL represents cellular changes with low potential for crossing into cancer cells, HSIL means that they have a high potential for crossing into cancer cells. The changes in the classification of the cellular changes resulted from the need for a more effective treatment and prevention of the most difficult consequences from untreated PAP test, which is cancer of the uterus. The three classification systems are presented in the table below.

Classification of the cellular changes
Description of the cellular changesSecond classification (1970 – 1990)Third (last)classification (1991 – today)First classification from 1943 (not in use)
Normal cells (without changes)NormalNormalClass I
Reactive or Neoplastic AtypiaAtypiaAGSCUS (2)Class II
HPV (Human Papillomavirus)HPVLSIL (the changes have low potential for crossing into cancer cells)Class II
Atypia with HPVAtypia (could be condylomatous or coilocytotic)LSIL (the changes have low potential for crossing into cancer cells)Class II
Mild dysplasiaCIN 1LSIL (the changes have low potential for crossing into cancer cells)Class III
Moderate dysplasiaCIN 2HSIL (the changes have high potential for crossing into cancer cells)Class III
Severe dysplasiaCIN 3HSIL (the changes have high potential for crossing into cancer cells)Class III
Carcinoma in situCa in Situ (CIS)HSIL (the changes have high potential for crossing into cancer cells)Class IV
Invasive carcinomaInvasive carcinomaInvasive carcinomaClass V


Description of the abbreviations:

  • CIN – Cervical intraepithelial neoplasia
  • ASCUS – Atypical squamous cells of uncertain significance
  • AGSCUS – Atypical glandular cells of uncertain significance
  • LSIL – Low grade squamous intraepithelial lesion
  • HSIL – High grade squamous intraepithelial lesion


What does the latest Bethesda classification from 1991 offer?

The latest classification simplifies the understanding of the PAP result because it only uses two options. According to it, the cellular changes are classified in LSIL or HSIL. From the table above, we can see that the previous findings such as HPV infection, condylomatous or coilocytotic atypia and CIN 1 are placed in the mutual group LSIL (low potential for crossing into cancer cells). The rest of the findings such as CIN 2, CIN 3 and CIS are placed in the group HSIL (high potential for crossing into cancer cells). This way the confusions regarding the PAP test are low.


How do the cervical cells change?

The cervical is the part of the uterus in the vagina and available for examinations. It is layered with two types of cells, one are flattened and cover the outside part, while the others are cylindrical and cover the inside part, i.e. the channel of the cervical. The transition zone from the first to the second cells is called transformative zone. The PAP smear is taken from this zone because it is the place where the cellular changes occur, such as dysplasia (pre-cancer) and cancer.

The term “plasia” means growth. When the normal growth is disturbed, the terms metaplasia and dysplasia are used.

Metaplasia represents a cell growth with a good prognosis (it is not cancerous). In this case a type of totally formed cells convert in another type of fully formed cells in order to handle the conditions of the changed environment. For example, fully formed cylindrical cells convert in fully formed flattened cells because of changes of the acidic environment in the vagina.

Dysplasia represents a growth of the cells when they only increase their number, but are not fully formed and don’t convert in another useful type of cells. Therefore, they have a different internal appearance. The bigger the level of dysplasia, i.e. of the unformed cells of the cervical, it is more probable that they will convert in invasive carcinoma. Because of this, the dysplasia is considered a “pre-cancer” state. The dysplasia is almost 100% curable if treated correctly. A small percent of the mild dysplasia (CIN 1) will withdraw without any treatment. But, it is not possible to predict which changes will withdraw, and which ones will change in the direction of cancer. The latest classification allocates these changes in the aforementioned two groups of cells (LSIS and HSIL).


Who or what causes the changes in the cells of the cervical?

All inflammatory processes in the vagina lead to a mildly abnormal PAP test which could be reported as: CIN 1, ASCUS or changes which are associated with the Human Papillomavirus (HPV). The inflammatory processes in the cervical make it look red, irritated or eroded, and it is misrecognized during the examination. In this case, the PAP test is delayed until the inflammation calms down or gets treatment.

Reasons for inflammation are:

  1. Bacteria (from infection);
  2. Viruses, especially herpes and condilomas (warts);
  3. Fungal or monilial infections;
  4. Trichomoniasis infections;
  5. Pregnancy, miscarriage or abortion;
  6. Chemicals (for example, medications);
  7. Hormonal changes.

All aforementioned cases can make the PAP test mildly positive. After treating the infection, the place recovers via metaplasia. Afterwards, the PAP test will be normal.


What to do when we are notified that the PAP test is positive?

According to everything that was said, when you receive the results of a positive PAP test, you should go to your gynecologist who should check whether the test is really positive. This examination is made with a colposcopy and with biopsy from the impacted areas. If he confirms the findings from the PAP test, then you will continue with a plan for a treatment of the changes.




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