Pre-cancerous lesions of Anal Canal
Screening for Anal Canal Cancer or precancerous lesions
The screening is done by either swab cytology of the anal canal or with the instrument which is used for colposcopy (high powered microscope)
Risk factors for anal cancer
Men who have sex with men (MSM) living with HIV have a high incidence of anogenital squamous cell carcinoma that is estimated to be 85 cases per 100,000 person-years, which is over four times higher than MSM (men having sex with men) without HIV (19 per 100,000 person-years) and 40 times higher than the general population (2.0 per 100,000 person-years)1.
The incidence of Ano-squamous cell carcinoma in MSM (men having sex with men) living with HIV has been on the rise attributed to prolonged anal high risk HPV infections (serotypes 16, 18, 58, 33, 45, 31, 52, 35, 59, 39, 51, 56). HPV16 causes 85% of ano-genital squamous cell carcinoma of all men having sex with men (MSM).
High risk (hrHPV) types (HPV 16, 18, 31, 33, 45, 52, 58) are responsible for the development of cervical (almost 90% of the cases), vaginal (70%), vulvar (40%), anal (80%), penile (50%), and oropharyngeal neoplasms (13–56%). Among high-risk
populations, such as men who have sex with men (MSM) and people living with HIV, there is a higher risk for anal cancer (37-fold higher) and for its potential precursor lesion, anal high-grade squamous intraepithelial lesion (HSIL)3.
Human immunodeficiency virus–positive MSM (men having sex with men) develop AIN (anal intra-epithelial neoplasia) and anal cancer more frequently than HIV negative MSM, and progression from normal findings or LSIL (Low-grade squamous intra-epithelial lesion) to HSIL (High grade intra-epithelial lesions) occurs fast2.
Anal Canal Cytology
Technique of anal Cytology for collecting the specimen
The goal of anal cytology is to identify patients with cellular changes in the epithelial cells that line the anal canal; any patients with atypia are then referred to undergo high-resolution anoscopy. No specific preparation is necessary before anal cytology, though patients should be instructed to refrain from receptive anal sex and enemas for 24 hours before testing. If a digital rectal examination is performed in conjunction with anal cytology, the cytologic sample must be obtained before lubrication is introduced into the anal canal. The standard technique used in obtaining anal cytologic specimens involves inserting a water-moistened Dacron swab into the anal canal to above the squamocolumnar transition zone, approximately 2 cm (1 inch) from the anal verge. While mild external pressure is applied to the anal wall, the swab is gently manipulated in a craniocaudal and circular motion within the canal. After several rotations, the swab should be withdrawn and immediately immersed in methanol-based preservative-transport solution.
Anoscopy by high powered microscope (Anoscope / colposcope) for screening for intra-epithelial tumors of anal canal
The patient is put in jack knife position to expose anal canal. The anal canal is opened by inserting a Anal retractor (Czerny rectal speculum)
The anal canal is then screened segment by segment. The anal skin is treated with acetic acid 3% to 5% to see any aceto-white lesions and then treated with Lugol's iodine. Any area that does not take up the iodine is suspcious area and biopsy is taken from that area.
Anal Canal Cancer
Symptoms of Anal Canal Cancer
- Peri-anal / anal itching - Frequent itching in peri-anal area
- anal or peri-anal pain - if there is pain or tenderness in or around anal area or in anal canal
- Bleeding per rectum (bleeding PR) - Frequent anal bleeding during passing of feces or even without motion
- Feeling of hardened area or lump close the rectal opening
- offensive anal discharge or smelly discharge
- altered or Improper bowel movements
- Durukan D, Phillips TR, Murray GL, Ong JJ, Grulich AE, Poynten IM, Jin F, Bradshaw CS, Aguirre I, Silvers J, Kent H, Atchison S, Balgovind P, Cornall A, Chen MY, Fairley CK, Chow EPF. Intra-Anal Imiquimod Cream against Human Papillomavirus Infection in Men Who Have Sex with Men Living with HIV: A Single-Arm, Open-Label Pilot Study. J Clin Med. 2021 Sep 28;10(19):4477. doi: 10.3390/jcm10194477. PMID: 34640496; PMCID: PMC8509144.
- Wieland U, Brockmeyer NH, Weissenborn SJ, Hochdorfer B, Stücker M, Swoboda J, Altmeyer P, Pfister H, Kreuter A. Imiquimod treatment of anal intraepithelial neoplasia in HIV-positive men. Arch Dermatol. 2006 Nov;142(11):1438-44. doi: 10.1001/archderm.142.11.1438. PMID: 17116834.
- Gkegkes ID, Iavazzo C, Stamatiadis AP. Intra-anal use of imiquimod: what is the clinical evidence? Int J STD AIDS. 2019 Sep;30(10):1018-1024. doi: 10.1177/0956462419855828. Epub 2019 Jul 8. PMID: 31284838.