Anal canal squamous-cell carcinoma in situ, clearly demonstrated by indigo carmine dye spraying: report of a case

Endoscopic submucosal dissection for early squamous cell carcinoma in the anal canal and Lugol chromoendoscopy for assessment of the lateral margin

A 66-year-old man underwent follow-up colonoscopy after colon polypectomy. The retroflexed view of the anal canal with white-light imaging revealed a whitish, slightly elevated lesion on the dentate line and an ill-defined flat lesion. A biopsy of the whitish elevation revealed squamous cell carcinoma (SCC), and endoscopic submucosal dissection (ESD) was planned. The lateral margin of the SCC was identified by spraying with Lugol's iodine, and the tumor was resected en bloc with no complications. The pathological findings were SCC in situ with parakeratosis in the whitish elevation and high-grade intraepithelial neoplasia in the ill-defined flat lesion, which exhibited a wide iodine-unstained area by chromoendoscopy. Early SCC in the anal canal is a rare gastrointestinal cancer, and Lugol chromoendoscopy helped visualize the tumor margin for ESD.

Neoplasia intraepitelial anal

Human papillomavirus (HPV) is responsible for anal condylomata, anal intraepithelial neoplasia (AIN) and anal squamous cell carcinoma. AIN is a premalignant condition that can progress to invasive carcinoma through different grades of severity of the disease called AIN I, AIN II and AIN III. This paper looks at the current definition, diagnostic methods and management of AIN. The incidence of AIN has increased significantly in the last decades. The groups at risk are mainly patients with infection with human immunodeficiency virus, immunossuppressed patients and patients affected by HPV related diseases (e.g., cervical cancer or anal condyloma). Accurate diagnosis of AIN lesions consists of accurate grading and disease extension. Low grade AIN (AIN I) or in extensive lesions, follow-up is advised to determine the possible evolution to anal squamous cell carcinoma. In cases of more severe and localized lesions (AIN II and AIN III), surgical resection should be considered if the predictive postoperative morbidity is low. Screening programs for AIN are not currently in place and there might be much effort to study the management of HPV in these patients.

Anal intraepithelial neoplasia

Background

Anal intraepithelial neoplasia (AIN) is believed to be a precursor of anal squamous cell cancer and its incidence is rising in high-risk groups, particularly those infected with the human immunodeficiency virus (HIV). The natural history of AIN is unclear and management strategies are lacking.

Methods

This review is based on a literature search (Medline and PubMed) with manual cross-referencing of all articles related to AIN.

Results and conclusions

The aetiology of AIN is intricately linked with human papilloma viruses. The pathological processes involved in the progression of AIN are becoming clearer but the natural history, particularly the rate of progression to invasive cancer, remains unknown. There is no standard management for AIN and this is mainly due to difficulties in both diagnosis and treatment. A variety of treatment options have been tried with varying success. Surgery is associated with significant recurrence, particularly in HIV-positive patients. Non surgical approaches with imiquimod, photodynamic therapy and vaccination are appealing, and further work is required. Long-term follow-up of these patients is essential until the natural history of AIN becomes clearer.