Anal Conditions: Anal Margin Tumors

Anal cancer represents a small percentage (approximately 2%) of all digestive cancers diagnosed each year. Tumors of the anus are divided into two categories: anal canal tumors and anal margin or perianal tumors. The anal margin or perianal region begins at the anal verge and extends radially for a distance of 5–6 cm. Anal margin tumors include squamous cell carcinoma, Bowen’s disease (perianal high grade squamous intraepithelial lesions, squamous cell carcinoma in situ), Paget’s disease (intraepithelial adenocarcinoma), basal cell carcinoma, verrucous carcinoma (giant condyloma, Buschke-Lowenstein tumor) and malignant melanoma. Effective treatment of anal margin tumors depends on recognition of atypical features on physical exam and prompt tissue diagnosis, particularly in patients with risk factors for anal cancer. In general, small superficial squamous cell tumors of the anal margin with no inguinal lymph node involvement can be treated with complete local excision. Radiotherapy can be added if excision margins are inadequate or for sphincter preservation. Combined modality of chemo-radiation is an initial treatment for squamous cell carcinoma of the anal margin that is larger in size, invades deeper tissue or involves inguinal lymph nodes. The optimum treatment of perianal high grade squamous intraepithelial lesions/HGIN/Bowen’s disease is controversial. Options include wide local excision with or without skin flap, high resolution anoscopy (HRA), topical therapy (5-FU, Imiquimod), photodynamic therapy, radiation therapy, and laser therapy. Paget’s disease, basal cell carcinoma and verrucous carcinoma are preferably treated with complete surgical excision. Wide local excision in the perianal region may result in a large tissue loss requiring skin graft, skin flap, or myocutaneous flap to cover the defect. Malignant melanoma of the anal margin is extremely rare with a poor prognosis. Treatment is local excision or APR; survival rates do not improve with radical surgery.