Malignancies of the anal margin and perianal skin.

Malignancies of the anal margin and perianal skin are relatively uncommon lesions, comprising 3 to 4% of all anorectal malignancies. Commonly included in this group of cancers are Bowen's disease (intraepithelial squamous cell cancer), perianal Paget's disease (intraepithelial adenocarcinoma), invasive squamous cell cancer, basal cell cancer, and malignant melanoma. Buschke-Lowenstein tumor, or giant condyloma acuminatum, is not always included because this lesion is technically benign, although it displays aggressive local invasive behavior that makes it difficult to manage. Complaints are usually nonspecific, such as itching or burning, bleeding, pain, drainage, or a mass. Proper diagnosis requires a high index of suspicion on the part of the surgeon. Innocent local irritations will resolve in a short time with appropriate therapy; those that persist must be biopsied for tissue diagnosis. Wide local excision is the mainstay of treatment for early stage tumors as it preserves continence and obtains adequate local control. Adjunct therapies have been utilized in more advanced or recurrent lesions, including radiotherapy, photodynamic therapy, and imiquimod. All have met with a fair amount of success in controlling local disease; however, the number of patients treated in each instance is small, making it difficult to design an evidence-based treatment strategy. Invasion and metastasis are relatively rare in this group of neoplasms; perianal Paget's disease has the highest risk of associated underlying neoplasm. The most important consideration in developing a treatment strategy is which strategy would achieve the best clinical result with the least morbidity to the patient.