[Perianal precancerous conditions (Bowen disease, Paget disease, Carcinoma in situ, Buschke-Lowenstein tumor)].

Perianal premalignant lesions are rare. Any suspicious perianal lesion or any perianal exanthema, that does not heal by non-surgical treatment has to be biopsied for histology. Many premalignant lesions are diagnosed as an incidental finding after anorectal surgery: any anorectal specimen must be examined by the pathologist. Leukoplakia is a facultative premalignant condition. High-grade anal intraepithelial neoplasia (AIN) is an in situ squamous cell carcinoma, associated with papillomavirus infection. Bowen's disease and Bowenoid papulosis are clinical variations of high-grade AIN. Buschke-Löwenstein tumour (giant condyloma) is a locally destructive tumour, that does not infiltrate or cause metastases. Paget's disease is a premalignant lesion like AIN, associated with other malignancies.