Cervical Intraepithelial Neoplasia (CIN; Dysplasia of the Cervix)

Introduction

Essentials of Diagnosis

• The presumptive diagnosis is made by an abnormal Pap smear of an asymptomatic woman with no grossly visible cervical changes.
  
• Diagnose by colposcopically directed biopsy.
  
• Increased in women with HIV.
  

General Considerations

The squamocolumnar junction of the cervix is an area of active squamous cell proliferation. In childhood, this junction is located on the exposed vaginal portion of the cervix. At puberty, because of hormonal influence and possibly because of changes in the vaginal pH, the squamous margin begins to encroach on the single-layered, mucus-secreting epithelium, creating an area of metaplasia (transformation zone). Factors associated with coitus (see Prevention, below) may lead to cellular abnormalities, which over a period of time can result in the development of squamous cell dysplasia or cancer. There are varying degrees of dysplasia (Table 17-2), defined by the degree of cellular atypia; all types must be observed and treated if they persist or become more severe. At present, the malignant potential of a specific lesion cannot be predicted. Some lesions remain stable for long periods of time some regress, and others advance.

Clinical Findings

There are no specific symptoms or signs of cervical intraepithelial neoplasia. The presumptive diagnosis is made by cytologic screening of an asymptomatic population with no grossly visible cervical changes. All visibly abnormal cervical lesions should be biopsied.

Diagnosis

A. Cytologic Examination (Papanicolaou Smear)
Specimens should be taken from a nonmenstruating patient, spread on a single slide, and fixed or rinsed directly into preservative solution if a thin layer slide system (ThinPrep) is to be used. A specimen should be obtained from the squamocolumnar junction with a wooden or plastic spatula and from the endocervix with a cotton swab or nylon brush.

Cytologic reports from the laboratory may describe findings in one of several ways (see Table 17-2). While use of class I-IV is now rare, the CIN classification continues to be used along with a description of abnormal cells, including evidence of human papillomavirus (HPV). The Bethesda System uses the terminology "squamous intraepithelial lesions (SIL)," low-grade or high-grade. Cytopathologists consider a Pap smear to be a medical consultation and will recommend further diagnostic procedures, treatment for infection, and comments on factors preventing adequate evaluation of the specimen. Reflex HPV testing of thin layer cytologic smears may be useful for triage of atypia (atypical squamous cells of unknown significance; ASC-US).