High-Resolution Anoscopy

CHAPTER 99 High-Resolution Anoscopy

J. Michael Berry, Naomi Jay

High-resolution anoscopy (HRA) is the examination of the anus and perianal region using a colposcope for magnification. It is a technique pioneered at the University of California, San Francisco (UCSF) in the Anal Neoplasia Study to determine the natural history of human papillomavirus (HPV)–related anal neoplasia. Similar to examination of the cervix, 3% acetic acid is applied to the anus and a colposcope is used to carefully examine the anal mucosa and perianal skin. Lesions can be identified using standard colposcopic criteria and sampled for histologic confirmation.

High-risk HPV types are found in up to 93% of anal cancers. High-grade anal intraepithelial neoplasia (HGAIN), including AIN grade 2 or 3 (moderate or severe dysplasia) or carcinoma in situ, are considered potentially precancerous lesions. It is believed that identification and eradication of HGAIN may prevent anal cancer, but studies demonstrating this principle have yet to be performed. The anus and cervix are similar biologically: both have a squamocolumnar junction, both are susceptible to the same types of HPV, and both demonstrate a similar spectrum of lesions. Because of these similarities, techniques for cervical cancer screening have been adapted for the anus.

In the United States in 2009 it was estimated that there were 5290 new cases of anal cancer, 2100 in men and 3190 in women. The incidence in the general population is 1.5/100,000. In human immunodeficiency virus (HIV)–negative men-who-have-sex-with-men (MSM), before the HIV epidemic, the incidence was estimated to be 35/100,000. Since the introduction of highly-active antiretroviral therapy, studies demonstrate an incidence twice that in several cohorts of HIV-positive patients, ranging from 78.2 to 92/100,000. The relative risk for anal cancer is increased to 4.68 (95% confidence interval 3.87–5.62) in women with a history of grade 3 cervical intraepithelial neoplasia (CIN) compared with women with no history.

Anal HPV infection can be found in more than 90% of HIV-positive MSM and approximately 60% of HIV-negative MSM. HRA with biopsy of suspect lesions found HGAIN in 52% of HIV-positive MSM, and in 16% of HIV-negative MSM at baseline in a cohort of men enrolled in the UCSF Anal Neoplasia Study between 1998 and 2000. A more recent population-based sample found rates of anal HPV infection of 57% in HIV-negative versus 88% in HIV-positive MSM. HGAIN was detected during HRA-guided biopsy in 25% and 43%, respectively.

In a study of 470 HIV-positive and 185 HIV-negative women, anal HPV was found in 80% of HIV-seropositive women compared with 50% of HIV-seronegative women. HGAIN was found in 9% of HIV-positive women and in 1% of HIV-negative women. In HIV-negative women with a history of CIN, 58% had anal HPV (slightly more than 30% had cervical HPV) and 15% had abnormal anal cytology. In women without a history of CIN who presented for sexually transmitted infection testing, 53% had anal HPV and 11% had anal squamous intraepithelial lesions. A group of 40 women with vulvar cancer were compared to 80 age-matched control women who were all examined with HRA. Coexistent HGAIN in 15 patients and 1 invasive anal cancer were found in the patients with vulvar cancer, compared with no cases of HGAIN in the control subjects.

Markov modeling demonstrated that anal cytology for anal cancer screening is cost effective every 2 to 3 years in HIV-negative MSM and every 1 to 2 years in HIV-positive MSM. In spite of these data, except for the state of New York, there are no official public health recommendations for screening programs. There are several reasons why routine screening programs have not been recommended in spite of convincing epidemiologic data. Data are just emerging demonstrating that HGAIN can progress to cancer. Currently, no controlled clinical trials have been initiated or completed demonstrating that screening and treatment of HGAIN prevent anal cancer. Another main limiting factor for screening is the lack of providers trained and experienced in performing HRA.

Ideally, HRA should be used to identify and target lesions for treatment because these lesions are largely invisible without the application of acetic acid and magnification. Data from several papers demonstrate that HGAIN can be effectively eradicated in many patients using an office-based procedure known as infrared coagulation. Patients with more extensive lesions are effectively managed with a combination of targeted surgical therapy of HGAIN guided by HRA coupled with office-based infrared coagulation to manage the inevitable recurrences. There was no evidence of HGAIN in 192 of 246 (78%) patients treated with this combined approach at their last follow-up visit.

Screening HIV-positive MSM with anal cytology and referring those with any level of cytologic abnormality can be recommended based on demonstrated cost effectiveness and increased prevalence of HGAIN and anal cancer. Some providers believe that if resources are available, HIV-positive MSM could be examined with HRA to maximize detection of HGAIN. For similar reasons, all MSM could be offered anal cytology screening. Because of the known association between high-risk HPV, high-grade CIN and vulvar intraepithelial neoplasia, and cervical and vulvar cancer, anal cytology screening may also be useful in women with these findings, followed by referral for HRA for any cytologic abnormalities.

Solid organ transplant recipients are at increased risk of anogenital cancer and may benefit from screening as well. Patients with perianal condylomata regardless of sex or sexual orientation may also benefit from screening.

Anal cytology screening in patients at increased risk for anal cancer requires that providers experienced in performing HRA be available to follow up on any abnormal results. HRA is a necessary requisite for a successful program in managing anal neoplasia because in the absence of palpable or visible lesions such as condylomata or anal masses, most HGAIN lesions are not visible or palpable.

Formal programs for certification, training, and standards in performing HRA have been created only recently. The first course in HRA was conducted in San Francisco in conjunction with the American Society for Colposcopy and Cervical Pathology (ASCCP) and coupled with this group’s Comprehensive Colposcopy course in August 2005. It is now offered annually.

Before learning HRA, providers should attend a formal colposcopy course and a formal didactic course in HRA, if possible. After basic colposcopy skills have been gained, attending an existing anal neoplasia clinic and spending several days observing HRA and the performance of anal biopsies in multiple patients is helpful. Further experience can be gained only by performing the procedure. Novices are advised to keep a logbook of all of their patients and to record their clinical and colposcopic impression. This can then be correlated with the cytologic and histologic results when they become available. This allows not only for patient follow-up, triage, and disposition, but for the clinician to develop and hone his or her clinical skills.

Anatomy

Like the cervix, the anus has a transformation zone (AnTZ) and a squamocolumnar junction (SCJ) where the anal squamous mucosa is adjacent to the colon columnar epithelium (Fig. 99-1). The SCJ is above the dentate or pectinate line. A similar process of squamous metaplasia occurs in the AnTZ, and dysplastic changes can occur during this dynamic time of transformation. When performing anal cytology, it is important to sample all areas of the AnTZ, just like in the cervix, so that cells are sampled from all areas. An adequate cytologic sample will have columnar or squamous metaplasia, which indicates that the AnTZ was sampled.

Figure 99-1 Anal anatomy.

Indications

Other than for a formal screening program for those at risk (MSM, anal-receptive intercourse, women with high-grade cervical and vulvar dysplasias/cancers, and organ transplant recipients), reasons patients may be referred for HRA include the following:

• Abnormal anal cytology of any degree

• Incidentally detected condylomata or HGAIN during colonoscopy

• Before hemorrhoidectomy or surgery for other benign anorectal conditions to rule out concurrent disease and allow treatment at the same time

• Perianal lesions, including condylomata, hyperpigmented lesions typical of Bowen’s disease, erythematous lesions, ulcerations, or masses

• Evaluation of anal symptoms such as irritation, itching, pain with bowel movements, bleeding or discomfort with receptive intercourse

• Self-detected lump or bump

• Prior history of anal condylomata, HGAIN, or anal cancer

• CIN, vulvar dysplasia

Contraindications

Severe neutropenia (<1000) is the one absolute contraindication to performing HRA. Current or past neutropenia or thrombocytopenia may indicate the need to defer biopsies or have current blood work available to determine the safety of performing biopsies.

Equipment and Supplies

Most of the equipment is the same as that used for a cervical examination (see Chapter 137, Colposcopic Examination). A procedure tray for HRA is shown in Figure 99-2. The tray includes the following:

• Cytology liquid medium (or conventional slide with fixative solution)

• Dacron swab (“Q tip”)

• Anoscope (disposable plastic or sterilized metal)

• 3% acetic acid

• Nonsterile cotton swabs

• Nonsterile scopettes

• Nonsterile 4 × 4 gauze pads

• Lugol’s solution

• K-Y jelly mixed with 1% to 5% lidocaine gel

• A 4 × 4 gauze wrapped around a cotton swab

Figure 99-2 A typical equipment tray for high-resolution anoscopy.

Additional Equipment for Biopsies

• Formalin bottles

• Baby Tischler or mini-Townsend cervical punch biopsy or endoscopy forceps

• Monsel’s solution

Preprocedure Patient Education

Patients should be told to refrain from inserting anything per anus for 24 hours before the procedure. This includes anal sex and insertion of any toy, medication, or enemas.

When discussing the procedure with patients, explain that a normal examination with biopsies will take 10 to 20 minutes. There are no pain nerve endings in the anal canal above the dentate line, only below it. The majority of lesions are above the dentate line and so biopsies are rarely felt beyond a sensation of minor pressure. The examination itself is not painful, but often there is mild discomfort associated with the pressure of the anoscope on the sphincter. Incontinence is rare, but patients should be told that the pressure will make them feel as if they need to have a bowel movement.

Medical history should include prior anal diseases, including abnormal cytology results, diagnoses of condylomata, low-grade anal intraepithelial neoplasia (LGAIN), HGAIN, or cancer, and any treatments used. In women, prior or current genital HPV-associated disease is important. A history of rectal abscesses, fistula tracts, fissures, or hemorrhoids can help determine potential sources of pain, bleeding, and scar tissue. Evaluate for history of immunosuppression or immune-suppressing drug therapy for organ transplantation, lupus, Crohn’s disease, or any disease requiring ongoing steroid therapy.

Complications such as severe bleeding and infection are rare. Scant bleeding after a biopsy may occur over a 1- to 2-day period and is not cause for alarm. Vasovagal reactions occur rarely.

Procedure

Anal Cytology

Anal cytology results are categorized according to the Bethesda classification system using terminology similar to that for cervical cytology. Anal cytology sensitivity for detection of anal neoplasia is comparable to that of cervical cytology, with a 25% or higher miss rate. The goal of anal cytology screening is to identify patients with HGAIN, who can then be treated. Cytology should be repeated every 2 to 3 years in low-risk patients and more frequently in high-risk patients (Fig. 99-3).

Figure 99-3 Anal cytology screening triage algorithm. AIN, anal intraepithelial neoplasia; ASC-H, atypical squamous cells, cannot exclude high-grade lesion; ASCUS, atypical squamous cells of undetermined significance; HGAIN, high-grade anal intraepithelial neoplasia; HIV, human immunodeficiency virus; HRA, high-resolution anoscopy; HSIL, high-grade squamous intraepithelial lesion; LGAIN, low-grade anal intraepithelial neoplasia; LSIL, low-grade squamous intraepithelial lesion.

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May 14, 2017 | Posted by admin in GENERAL & FAMILY MEDICINE | Comments Off

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