cervix chapter aca

Uterus: Cervix Overview

Normal Anatomy

The cervix serves as a crucial anatomical structure that connects the uterus to the vagina through the endocervical canal. It is divided into two primary segments:

• Portio Vaginalis: This portion protrudes into the vaginal lumen and is what is generally examined during a pelvic exam.

• Supravaginal Portion: This segment lies above the vaginal vault, residing within the pelvic cavity.

Exocervix (Ectocervix)

The exocervix is the outer surface of the portio vaginalis and is covered by nonkeratinizing stratified squamous epithelium, which provides a protective barrier against mechanical and chemical insults.

Endocervical Canal

Lined by columnar mucus-secreting cells, the endocervical canal plays a pivotal role in menstrual cycle regulation and protection against pathogens. It opens at the external os, serving as a passage for menstrual fluid and childbirth.

Transformation Zone

This zone is a significant anatomical area where the squamous and glandular epithelia converge. It is particularly important in the context of cervical pathology as it is a site where metaplasia, a process associated with precancerous changes, frequently occurs.

Key Cervical Structures

Cell Layers in Exocervix:

• Basal Cells: These are the fundamental building blocks of the epithelium, playing a vital role in regeneration.

• Stratum Spongiosum (Midzone): This layer contains the suprabasal layer situated above the basal layer, providing both structural support and flexibility.

• Superficial Layer: Composed of mature squamous epithelial cells, this layer is crucial for barrier function.

Histochemical Features:

• Basal Layer: Positive staining for low-molecular-weight keratin and tissue polypeptide antigen (TPA) indicates active cellular processes. The layer is notably negative for high-molecular-weight keratin, highlighting its unique characteristics.

• Glandular Epithelium: This epithelium shows variable reactions to mucin based on the menstrual cycle, reflecting hormonal influences.

Remnants and Ectopias

• Mesonephric Rests: Represent remnants of the wolffian ducts and are identified in approximately one-third of women, which can sometimes lead to confusion in diagnosis.

• Ectopic Tissues: Include cutaneous adnexa such as sebaceous glands and hair follicles, as well as prostatic tissue, mature cartilage islands, and various forms of squamous and other metaplasias.

Squamous and Other Metaplasias

Types:

• Squamous Metaplasia: Involves the replacement of glandular epithelium by stratified squamous epithelium, particularly common around the transformation zone. The pathogenesis often includes proliferation of reserve cells or ingrowth of native squamous epithelium, complicating the diagnosis due to similarities with squamous intraepithelial lesions (SIL) or cervical intraepithelial neoplasia (CIN).

• Transitional Metaplasia: Frequently observed in the context of atrophy among older women.

• Tubal Metaplasia: Characterized by the presence of cell types normally found in the fallopian tubes; it poses significant diagnostic challenges for pathologists.

Non-Neoplastic Glandular Lesions

• Endocervical Polyps: Resulting from chronic inflammation, these lesions can present with microscopic dilated endocervical glands, causing symptoms like abnormal bleeding.

• Malakoplakia: This rare lesion typically indicates a possible association with involvement of other organs and reflects a chronic inflammatory response.

• Ceroid Granuloma: Exceptionally found in the cervix, this indicates an atypical response to inflammation.

• Nabothian Cysts: Develop due to blockage of endocervical glands, are benign, but can extend into the cervical wall, occasionally mimicking malignancy.

• Microglandular Hyperplasia: Involves proliferation of small glands, which can mimic malignant processes, requiring careful evaluations using immunohistochemistry for accurate diagnosis.

Inflammatory Lesions

Chronic Cervicitis

Characterized by hyperemia and edema, this condition commonly affects the squamocolumnar junction and may produce various symptoms, including discharge and discomfort.

Infections:

• Herpes Simplex: Generally, this infection results in nonspecific inflammatory changes.

• Chlamydia Trachomatis: Recognized as the most prevalent venereal disease, it can lead to chronic inflammation without visible organisms on standard histological examination. Other infections, including syphilis, can present similarly and necessitate careful differentiation from neoplastic changes.