Anal Warts and Anal Intradermal Neoplasia

Abstract

For the last five millennia we have been dealing with the annoyance of verrucas. Anogenital human papillomavirus (HPV) infection is the most common sexually transmitted disease in the United States and is increasing in incidence. As in other gastrointestinal conditions, HPV infection can lead to a stepwise transition from normal cells to dysplastic cells and then to invasive anal cancer. Knowledge of the natural history of HPV infection, risk factors, diagnostic tools, and therapeutic methods gives us the tools to adequately prevent, evaluate, treat, and counsel our patients. In this review, the authors detail the diagnosis, management, and treatment of anal condyloma and anal intraepithelial neoplasia with a focus on prevention, early detection, and treatment using current data and technology.

Barley-corn, barley-corn, injun-meal shorts, Spunk-water, spunk-water, swaller these warts… .
“Adventures of Tom Sawyer”
Mark Twain, 1846

HISTORY OF HUMAN PAPILLOMAVIRUS

Condyloma acuminata is a sexually transmitted disease caused by some groups of human papillomavirus (HPV) that have a high affinity for genital epithelium. For almost five millennia, warts have been a documented source of annoyance, shame, and impurity (Table 1). Verrucas have been found on an Egyptian mummy from 2400 BC.¹ Warts also are mentioned in the Old Testament and in ancient Persian's Zoroastrians Code (1200–1500 BC).² In first-century Rome, Aulus Cornelius Celsus' De Medicina discussed how to treat warts by applying heat from ashes of the lees of wine. In the 17^th to the 19^th century, poor hygiene, syphilis, and gonorrhea were thought to be the cause of genital warts.³ In 1876 Marks Twain's infamous character, Tom Sawyer, contracted warts from playing with frogs and used folkloric treatments to remove them. In 1933 Richard Shope described the papillomavirus, “Shope virus,” and later, in 1949, Strauss identified intranuclear inclusion bodies in human skin papillomas using an electron microscope.^4,5 In 1976, Harald zur Hausen discovered an association between cervical cancer and HPV; 10 years later he identified the HPV genetic subtypes 16 and 18.^6,7 The identification of integration patterns and expression of the early genes E6 and E7 in cervical cancer led to the creation of the HPV vaccine. Harald zur Hausen was awarded the Nobel Prize for Physiology and Medicine in 2008 for his work on HPV.

Table 1.

Human Papillomavirus (HPV) Historical Timeline

2009	HPV Vaccine for men
2008	H zur Haussen wins Nobel Prize
2006	HPV Vaccine for women
1986	H zur Haussen: HPV 16/18, E6 E7
1976	H zur Haussen: HPV and cervical cancer
1949	Strauss: HPV particles w/electron microscope
1933	HPV: Shope's Virus
1876	Mark Twain folkloric treatment
1700	Gonorrhea: syphilis condyloma lata
100 AD	Celsus' De Medicina: three types of warts
1200 BC	Persia's Zoroastrians Code: warts and STDs
1400	Leviticus Bible
2500	Egyptian mummy

INCIDENCE OF AIN

Recent literature has demonstrated a significant increase in anal intraepithelial neoplasia (AIN), but the actual overall incidence is unknown.⁸ The CDC has estimated that 75 to 80% of sexually active Americans will likely acquire genital HPV at some point in their lives.⁹ This increase is even more significant in men who have sex with other men and immunocompromised patients. A study in England and Wales showed that from 1971 to 1994 there was a 390% and 594% increase in genital warts for men and women, respectively.¹⁰ The duration of HPV infections in the majority of healthy individuals is limited. Most infections clear in a very short time and may go unnoticed.¹¹ The subclinical presence of anal HPV infection in asymptomatic homosexual men (evaluated using anal inspection, anoscopy, and anoderm cytology) has been reported to be from 31 to 65%.¹²

Other risk factors for increased incidence of HPV include

• Immunosuppression; organ transplant patients

• Women with a history of cervical disease or neoplasia

• Men and women with more than 10 female sex partners

• Patients with a history of anogenital warts or prior history of sexually transmitted diseases (STDs)

• Human immunodeficiency virus (HIV) infection

• Cigarette smoking

• Radiation therapy^13,14

PATHOPHYSIOLOGY OF THE HPV VIRUS

The HPV virus has a high affinity for the transitional zones of the cervix and the pectinate line of the rectum at the squamous–columnar junction (SCJ) epithelium. The HPV virus targets the basal membrane stem cells.^15,16 This is where virus replication occurs. The HPV virus has a very slow progression from the initiation of genetic transcription, contributing to the effectiveness of the vaccine.¹⁶ The genome of the HPV virus is composed of several early and late genes. The late genes, L1 and L2 are used for the HPV virion's infection into the cells of the basal membrane; the early genes (E1–E8) are used in the expression of the infection.^16,17 Frequently, the body's cellular immune system deactivates these early genes before progression of the virus life cycle; however, if inoculation of the virus into the cell's DNA occurs, the early genes (E1, E2) are expressed. Other early genes promote the proliferation of epidermal cells; as a result, the superficial cell layer becomes thicker, forming the rough hills of condylomatous lesions. The early gene E6 proteins can decrease p53 activity. The loss of this tumor suppressor protein allows the virus to replicate.¹⁸ It also can predispose one to cancer formation, with half of all known cancers containing a p53 mutation/deactivation.¹⁹

Clinical Presentation and Examination

Standardized anatomic description is important to adequately communicate findings on physical examination. Four distinct regions has been proposed for description⁸:

• Skin: 5 cm away from the anal opening upon simple examination

• Perianal (anal margin): within 5 cm of the anal opening

• Anal canal (Intra-anal): not visible, needs anoscopy to see

• Transformation zone: above the dentate line/squamous columnar junction

Symptoms

Patients initially present with a wide range of symptoms that may be vague, moderate, or severe. Symptoms may include itching, anal discharge, discomfort, tenesmus, and changes in bowel habits, fissures, masses, or fistulas.

Condyloma acuminata (Greek words meaning knuckle or knobs and pointed or tapered) are often easily identified.

The clinical appearance can be obvious or can be more obtuse with swelling, flaking, oozing, irregular, scaling, white or pigmented plaques in the anal area. Anogenital warts can be characterized in three ways:

1. Classical: cauliflower, acuminata like, knuckles, horny with pointy edges (Fig. 1)

2. Smooth: exophytic, papulous appearance with hill-like, raised edges

3. Flat: non-exophytic, plaques that may require high-resolution anoscopy for identification

Figure 1.

External exophitic condyloma acuminatum.

Evaluation of patients should consist of a full proctologic examination: inspection, palpation, anoscopy, and sigmoidoscopy. Many practitioners augment their examination with anal cytology or high-definition anoscopy with acetic acid or Lugol solution. HPV-DNA testing and endorectal ultrasound may be added before biopsy in patients with lesions suspicious for invasion.

ANAL INTRAEPITHELIAL NEOPLASIA/ANAL DYSPLASIA

Anal intraepithelial neoplasia (AIN) is defined as an abnormal growth of dysplastic cells in the anal area. The first use of this term was by Fenger and Nielson after they identified unexpected dysplastic changes in routine pathologic specimens.²⁰ Dysplasia is diagnosed when abnormal epithelial cells are present with specific characteristics: anisocytosis, increase in mitotic cells, abnormal size nuclei, and hyperchromatism.²¹ The diagnosis of AIN can be made with anal cytology or tissue biopsy, but there can be a difference in interpretation of the grade of dysplasia.^21,22

The type of HPV virus that is present may have an influence on the presence of AIN. There are around 30 known HPV types of viruses that affect the perianal area. The HPV subtypes 6 and 11 are the cause of over 90% of the exophytic anal warts. They tend to be associated with low-grade dysplastic cellular changes (AIN 1).²¹ On the other hand, HPV types 16 and 18 are responsible for most of the chronic infections that cause severe dysplasia (AIN 2 or AIN 3) and the development of cancer.^8,23 As a rule AIN 3, also known as carcinoma in situ, is diagnosed when 50% of the epithelial tissue is replaced with abnormal dysplastic cells. Unfortunately, it is not possible to culture HPV from the affected tissue and there is no reliable serologic test for HPV infections.²⁴

AIN AND HIV

Immune-deficient patients (especially those infected with HPV-type 16 or 18) are typically unable to prevent the propagation past the production of the early expression HPV virons proteins (E2, E6, E7) leading to an associated increased risk of high-grade dysplasia/AIN 3.²⁵ Studies have shown that patients who are HIV-positive with a decreased CD4 lymphocyte count have a higher risk of HPV infections and of high-grade AIN 3, important risk factors for the development of anal cancer.^26,27

Although the natural history of HPV anal infections is not clearly understood, chronically infected tissue has been shown to progress to more severe disease in 62% of HIV-positive men and 36% in HIV-negative men.²⁶ When the anal margin is the original site of infection, it is mostly associated with low-grade changes (AIN 1). On the other hand, infection in the anal canal is more commonly associated with higher-grade lesions (AIN 2,3). Thus location is an important risk factor as well.^26,27,28 It is also known that anal cancer is usually preceded by high-grade AIN, which is more frequent in HIV-positive MSM (men having sex with men). The use of highly active antiretroviral therapy (HAART) has not been shown to decrease or resolve AIN. Although a low CD4 count appears to be associated with an increase in AIN, patients on HAART do not have a decreased risk of having AIN lesions.²⁹ In short, all patients who are HIV-positive are at increased risk of having HPV and AIN.

Anal Cytology

Considering the similarities to cervical cancer, several practitioners have demonstrated feasibility and recommend anal cytologic evaluations in HIV-positive patient populations.^{21,30,31,32,33} Obtaining a sample for cytology is a simple procedure. It is important that before anal cytology is performed the patient be aware that an abnormal result may mean further testing. Anal cytology is done by inserting a moist Dacron swab or a cytobrush into the anus and rotating it to collect the cells. The collected cells are then passed to an approved liquid medium or to a glass slide, if no liquid base is available. The sample obtained is evaluated and reported using the Bethesda Classification (parallel to a Papanicolaou (Pap) test). No enemas are needed, but patients should avoid anal sex for 24 hours before anal cytology is performed.³⁴

Developed in 1988 and later modified in 2001, The Bethesda Classification is used to describe cytologic findings. Results are classified as normal, atypical squamous cells of undetermined significance (ASC-US), low-grade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesion (HSIL), or squamous cell carcinoma. ASC-US are the pathologic abnormal cytological cellular changes that are not severe enough to meet the criteria of a squamous intraepithelial lesion (SIL).

Patients who are found to have abnormalities on cytologic screening are typically referred for high-resolution anoscopy and/or biopsy. This follow-up biopsy is of paramount importance because anal cytologic evaluations are highly sensitive for dysplasia (positive predictive value of 95.7%), but have a low specificity with regards to identification of high-grade dysplasia (55.9% positive predictive value for high-grade dysplasia).³⁵

High-Resolution Anoscopy

High-resolution anoscopy is an important tool in the evaluation of a patient with possible AIN. It can be done in an office setting or in the operating room. The standard technique of performing this diagnostic test is to treat the anal area with 3% acetic acid for a few minutes and then insert a disposable anoscope and evaluate under 10 × to 15 × magnification. The acetic acid tissue reaction causes the dysplastic tissue to appear whitish. The squamous–columnar epithelial area is examined looking for “acetowhite” (ACW) and for abnormal vascular changes such as punctuation and mosaic patterns. Lugol solution can also be used and suspicious areas with AIN should appear yellow versus the normal tissue's brownish background. Biopsies of the abnormal areas should be done. This procedure can be performed by a large number of specialists such as gynecologists, general surgeons, colorectal surgeons, dermatologists, internists, pediatricians, infectious disease physicians, and others. Other alternatives such as magnified loupes or an operating microscope can be used if high-resolution anoscopy is not available, but they are not the recommended techniques.

DNA with Pap Hybrid Capture 2

The DNAwithPap™ test (Digene Corp., Gaithersburg, MD) is done at the time of a cytologic test. It detects the DNA of 13 high-risk HPV types (16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68) and of 5 low-risk types (6, 11, 42, 43, and 44). A positive result determines that either the high- or the low-risk types are present.³⁶ The sensitivity of the HC-2 test has been shown to be over 90% in AIN 3 with a negative predictive value of 99%. The pitfall for this test is its specificity of 87.3% with a regular Pap test and 85.6% with liquid-based Pap.³⁷

Emotional Aspects

Being the primary physician for a patient with HPV can be challenging. The embarrassment associated with a medical problem in the perineum is understood even from the meaning of the word pudendal, the area of the external genitalia and perineum, which in Latin means “shame.” If we add the stigma of a STD and the surrounding questions of how it happened, we can understand the delicate situation at hand. Because 90% of warts are found in low-risk patients, most patients can be reassured that there is a good possibility that they will not be chronically affected and are unlikely to develop anal cancer. In a study of Swedish women with genital warts, more than half of the females reported symptoms of fear, anger, guilt, and disgust regarding their diagnosis.³⁸ The FDA approval of the “quadrivalent” vaccine against HPV types 6, 11, 16, and18 may give hope and additional protection to those who do not have HPV both in low- and high-risk groups.

Differential Diagnosis

It is likely that perianal Bowen's disease and high-grade AIN 3 have a common etiology of types 16 and 18 HPV.³⁹ Other perianal pathologic skin appearances that can be present and must be ruled out are Paget's disease, herpes, secondary syphilis' condyloma lata (flat skin lesions), reactive atypia in squamous metaplasia, squamous hyperplasia, Haemophilus ducreyi chanchroids, and molluscum contagiosum (condyloma subcutaneum). A correct diagnosis is usually accomplished by a biopsy.

Treatment

The treatment of HPV depends on several factors. These include extent and location of disease, extent of atypia, and patient-related factors. Perhaps the easiest way of breaking this down is by separating patients into two groups. The first is composed of those patients who are at low risk of developing anal cancer. These patients have normally functioning immune systems and are without dysplasia on biopsy of their anal lesions. Patients in the second group are those patients who are at increased risk of developing anal cancer, including patients with dysplasia on biopsy and those with immune system compromise. By thinking in these terms, the risks, benefits, options of treatment, and follow-up evaluations of our patients become easier to consider.

Numerous comparisons between therapy choices and follow-up have been made, but unfortunately, there are no large randomized studies in this area. Consequently definitive recommendations are difficult to make. A recent survey of surgeons and dermatologists in Europe gives an interesting glimpse at the lack of consensus among experts who treat patients with HPV. In the survey, 91% of surgeons preferred excision as the treatment of choice compared with 57% of dermatologists. Further, dermatologists were much more likely to utilize topical agents (imiquimod or podophyllin).⁴⁰ Consensus is clearly lacking and this will likely persist until larger, more controlled studies are done.

LOW-RISK HPV PATIENTS

Of patients who present with anal HPV infections, 74% of non-HIV positive patients and 38% of HIV-positive patients have been found to have benign condylomata on biopsy without evidence of dysplasia or cancer. Progression from benign disease to dysplasia is rare in immunocompetent patients.⁴¹ For these patients, the most important feature of their disease is its extent. For patients with limited disease, local excision to obtain a pathologic evaluation and destruction is considered the treatment of choice. The choices for therapy are extensive. Treatment may entail excision, destruction with electrocautery, CO₂ laser, cryotherapy, trichloroacetic acid (TCA), or infrared coagulation. Further, topical application of podophyllotoxin or imiquimod has been shown to be effective as well. Each of these methods has its champions, but none are clearly superior to others.

Local excision and destruction using electrocautery has been shown to be safe without significant risk of anal stenosis.⁴² The advantage to this approach is that it allows one to evaluate the anal canal under anesthesia and potentially complete therapy in one setting. Gynecologists have employed laser treatment with excellent results as well.⁴³ Others have utilized infrared coagulation with reportedly good success.

For small lesions, treatment in the office with topical (TCA) or cryotherapy has the advantage of being quick, easy to conduct, and inexpensive.

With regards to topical home therapy the most popular options are imiquimod and podophyllotoxin. These treatments have the advantage of avoidance of surgical procedures and surgical complications and the topical agents have the ability to treat large areas without untoward collateral damage. Interestingly, women have been found to respond better to immunotherapy with topical imiquimod than men.^44,45 In 2006, Yan et al compared imiquimod to podophyllotoxin and found that cure rates were not statistically different between the two agents (50.3% and 56.4%, respectively), but that the side effects were more severe with podophyllotoxin.⁴⁶ Topical therapy may be most appropriate for patients with extensive disease because excision or destruction of their lesions could be quite morbid or require a staged procedure. One must understand that a significant percentage of patients will be nonresponders to imiquimod or unable to tolerate the therapy and thus require excision/destruction of their lesions.

Because both ablative and topical therapies have their respective advantages, perhaps a combination of ablative therapy and topical therapy may be our best approach. In 2006, Schofer et al published their results of a three-arm study of immunocompetent patients with external condylomatous disease comparing ablative/excision therapy alone, ablative/excision therapy followed by imiquimod, and imiquimod therapy alone. Destructive therapy had an initial clearance rate of 92% compared with 65% with imiquimod alone. Only patients with an initial treatment success were included in the study and a significant number of the patients (21%) in the two imiquimod groups were lost to follow-up (perhaps because the therapy is difficult to tolerate). Still, the study found that recurrence rates were statistically lower at 6 months in the two arms that used imiquimod when compared with the arm with ablative therapy alone (93.7% and 91.5% versus 73.6%).⁴⁷ From this study, we can conclude that initial clearance of disease is best achieved with destruction/excision and recurrence is lowest if patients are treated with topical imiquimod therapy following destruction/excision.

HPV WITH ATYPIA/HIGH-RISK PATIENTS

The finding of atypia within condylomatous lesions is not at all uncommon. Atypia on biopsy has been reported at rates of 14 to 35%. This finding is much more common in HIV-positive patients.^41,48,49 In their 10-year experiential chart review of their anal condyloma patients, Anderson et al found that 5 out of 33 patients with benign disease had disease progression (to high-grade dysplasia, verrucous carcinoma, or moderately differentiated carcinoma) with a mean time to progression of 84 months. Four out of 5 of the patients who had progression of disease were HIV-positive. They conclude that recurrent condylomata in HIV-positive patients should be biopsied.⁴¹ Disease progression from benign to malignant in the anal canal is much more common in the immunosuppressed patient indicating a significant increased risk of cancer development in this patient population. Indeed, the realization that HIV leads to increased dysplasia has been in the literature for a quarter century.⁵⁰

Likely due to frustrating recurrence rates, many practitioners have elected to follow their patients with AIN with expectant management/close clinical follow-up rather than efforts to eliminate disease. Supporting this, some studies indicate that our ability to eliminate dysplasia without having recurrence is limited.⁵¹ There is an ongoing debate about the appropriateness of expectant management of patients with AIN. Advocates point out that most patient's with dysplasia do not progress to cancer and that those who do can often be treated with local excision or chemo–radiation rather than radical surgery.⁵² However, others argue that expectant management has been shown by several practitioners to result in potentially high rates of progression to anal cancer and significant morbidity with treatment, especially in HIV-positive patients.^28,53,54 Although potentially tedious, destruction of dysplastic anal lesions has been shown to be feasible and is likely more appropriate than watchful waiting. At the heart of this debate may be the unfortunate fact that high-resolution anoscopy is not an active part of most colorectal surgeons' practices. Therefore, their ability to effectively detect and obliterate dysplastic lesions is limited.

Treatment options for patients with dysplasia on biopsy and/or those with immune system compromise is not very different from those with more benign disease except for the addition of high-resolution anoscopy. Without high-resolution anoscopy, patients with large circumferential lesions are subject to multiple random circumferential biopsy and extensive nontargeted destructive therapies.

In their 10-year experience summary at Stanford utilizing high-resolution anoscopy-directed biopsy and destruction with electrocautery of anal lesions, practitioners were able to clear 78% of patients of their high-grade squamous intraepithelial lesions. Naturally, this excellent result required significant vigilance with close clinical follow-up with anal cytology and high-resolution anoscopy accompanied by office-based and surgical retreatment of more than half of the patients (average time to recurrence of 19 months, range 3 to 92 months). Still, this result is encouraging, especially considering that 74% of their patients were HIV-positive and only 3 patients (1.2%) progressed to anal cancer.⁵⁵ Nathan et al also showed that destruction of AIN lesions is quite feasible with a 63% cure rate at one year.⁴³

Another option for patients with dysplasia is topical imiquimod. As previously noted, it is effective in controlling condyloma in many patients. Similarly, it has been used effectively to induce regression of AIN with a complete response rate of 48%, partial response rate of 34%, and a recurrence rate of 36%.⁵⁶

Follow-Up

In their European survey, Dindo et al found that there was a consensus among practitioners with regards to follow-up for patients found to have atypia on biopsy. The median surveillance interval for physical examination for dermatologists and colorectal surgeons alike was 6 months in HIV-negative patients with low-grade AIN and 3 months for HIV-positive patients with low- and high-grade AIN.⁴⁰ This begs the question, “Is there any data to support this surveillance regimen and what sort of follow-up evaluations are needed?”

In a retrospective review of postoperative condyloma patients, de la Fuente et al found that immune status was extremely important with regards to recurrence of disease. When compared with immunocompetent patients, immunosuppressed patients recurred more often (66% vs 27%) and more quickly (6.8 mos vs 15 mos).⁵⁷ These data support closer follow-up of immunosuppressed patients and appear to support a follow-up regimen of at least every 6 months for immunocompromised patients and yearly for immunocompetent patients.

In a study from San Francisco, 32% of HIV-positive men who had no anal disease at the time of entry into the study had AIN I diagnosed within 2 years, compared with 9% of HIV-negative men. In the same study, 30% of those with AIN I at baseline had no disease at 2-year follow-up (all were HIV-negative). Conversely, AIN I often progressed to AIN II or AIN III in HIV-positive patients (> 50% progressed within 2 years).²⁶ Further, once AIN II or AIN III is found, it rarely regresses, even in HIV-negative individuals.⁵⁸ In higher-risk patients, close follow-up is absolutely warranted.

Anal Cytology

Recently, the New York State Department of Health AIDS Institute gave the recommendation that clinicians should obtain anal cytology at baseline and annually in HIV-infected men who have sex with men, patients with a history of anogenital condylomas, and women with abnormal cervical and/or vulvar histology. Analyses of cost-effectiveness appear to indicate that cytologic screening (every 2 to 3 years) to prevent anal cancer may be cost-effective.^59,60 Still, anal cytologic evaluations have not yet become mainstream procedures.

DISCUSSION

As the incidence of anal condyloma increases and advances are made in the field, we practitioners must make appropriate adjustments or we will find ourselves rendering outmoded care. Adding to our difficulties is our reliance upon our pathology colleagues to aid us with appropriate diagnoses. The use of the terms high grade or low grade as used in other areas of the gastrointestinal system will likely improve interobserver communication, avoiding bias and confusion. Today, histologic descriptions may be causing some confusion. Perhaps the use of the term low-grade dysplasia to describe AIN 1 and high-grade dysplasia to describe severe dysplasia, AIN 2, AIN 3, and carcinoma in situ would alleviate some of this confusion and help practitioners decide the next most appropriate step for their patients.

As surgeons, there is certainly a need to change the way we practice. There is evidence supporting the practice of anal Pap exams, and a need to learn new techniques and obtain new equipment such as high-definition anoscopes. Embracing these changes will be essential, as we are now in a new era in the treatment and counseling of patients with HPV. In keeping with this, several multidisciplinary specialist clinics and centers focusing on patients with HIV and HPV have begun appearing around the country. We certainly applaud these efforts.

Wearing condoms, avoiding shared sexual or genital objects, and quitting smoking if infected, are some basic recommendations in dealing with an HPV infection. Still, the issue of prevention is a public health issue that needs specific attention. The ability of the HPV vaccine to decrease the incidence of low- or high-grade dysplasia has not yet been demonstrated. However, we are hopeful that these data will be forthcoming and anticipate that engaging in the modern practices of HPV treatment will significantly decrease the impact of this disease on our patients.