Degrees of cervical dysplasia

When diagnosing cervical intraepithelial neoplasia, also known as interstitial neoplasia or - in the more familiar definition for domestic gynecology "dysplasia of the cervix" - it is customary to determine the level of pathological tissue growth. And depending on this, degrees of dysplasia of the cervix are distinguished.

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Main degrees of cervical dysplasia

Cervical dysplasia grade 1 - CIN I (LSIL according to Pap smear) or mild cervical dysplasia - is determined when patients are found to have HPV (HPV) - papillomavirus, which is the cause of cervical oncology in 99% of cases. In this case, minor proliferation is detected in the epithelial cells of the lower 30% of the basal layer, and in the upper layers, the cytopathic effect of the papilloma virus is observed: atypical cells with perinuclear cavitation or halo in the cytoplasm.

This is the least dangerous degree of dysplasia. Foreign gynecologists note that treatment of a mild degree (CIN I) is not recommended if the process lasts less than two years: the patient's immunity can cope with HPV within 12 months. Although here everything depends on the state of the body's defenses.

Cervical dysplasia grade 2 - CIN II (HSIL according to Pap smear) - or moderate cervical dysplasia differs from grade 1 by a deeper lesion of the epithelium (by 50% of the thickness). In this case, the affected part of the epithelium consists of undifferentiated cells that have changed in shape and size.

Cervical dysplasia grade 3, involving 70-90% of the epithelial thickness, is defined as severe cervical dysplasia or CIN III (HSIL by cytology). Dysplastic cells are most often distributed throughout the entire thickness of the ectocervix.

Atypicality in the form of nuclear and cytoplasmic changes in epithelial tissue cells is expressed in an increase in their mitotic division, in which the nuclei increase in size and are intensely stained, which is an anomaly for epithelial cells. Hyperchromatosis of nuclei confirms the intensive proliferation of epithelial cells, characteristic of neoplasia. In this case, differentiation and stratification may be completely absent or present only in the upper layer of the epithelium (with multiple mitosis).

This pathology is often defined as carcinoma in situ, but the CIN III degree is not cancer, but a precancerous condition. If severe cervical dysplasia is not treated in time, it can spread to adjacent normal tissues and become cancer. According to the NCI, in 20-30% of cases, such dysplasia undergoes malignancy and leads to squamous cell carcinoma.

But grade 4 cervical dysplasia is invasive cancer. In the past, it was thought that progression to cancer occurred through all of these grades of cervical dysplasia in a linear fashion. According to the NCI, progression to invasive cervical cancer occurs in approximately 1% of grade 1 dysplasia cases, 5% of grade 2 cases, and at least 12% of severe dysplasia cases.

The overall level of malignancy of dysplasia is approximately 11% of cases of mild pathology and 22% of cases of moderate pathology. At the same time, spontaneous regression of the disease is observed within 12 months in almost 70% of patients with mild dysplasia, and within 24 months in 90%. About 50% of cases of moderate cervical dysplasia also tend to spontaneous regression.

How are the degrees of cervical dysplasia different?

Previously, pathological changes in the squamous epithelium of the cervix - degrees of cervical dysplasia - were defined as mild, moderate or severe. But for more than a quarter of a century, the terminology system proposed by the American National Cancer Institute (NCI) has been in effect, developed in accordance with the Cervical Cytology Atlas created by specialists of the American Society of Cytopathology (ASC), periodically republished by the American publishing house Bethesda Softworks (that is why the system is called the Bethesda system).

The creators of the system tried to unify the definitions of the results of cytological studies of the ectocervix of the cervix, carried out by taking a pap smear (smear according to Papanicolaou) and histological studies of a tissue sample (biopsy). Cytological changes in dysplasia are defined as damage to the squamous epithelium (SIL) and have degrees: low (LSIL), high (HSIL), possible cancer (malignant) and atypical glandular cells (AGC).

Histological changes are expressed by the term cervical intraepithelial neoplasia (CIN), their degrees are I, II and III.

The descriptive system still uses the terms mild dysplasia, moderate cervical dysplasia, and severe cervical dysplasia.

When a doctor indicates that a patient who has undergone the test has cervical dysplasia of grade 0, this means that the cytological analysis results show normal squamous cell epithelium, and histology also did not reveal any pathological changes in the tissues of the cervix.