PURPOSE:Extramammary Paget's disease of the perianal region is a rare finding that often results in delayed diagnosis and treatment. Although the natural history of the disease is not well characterized, it historically has been associated with other cancers. This study summarizes the history and treatment of all patients diagnosed with perianal Paget's disease at a single institution.METHODS:Charts of all patients with a diagnosis of extramammary Paget's disease of the perianal region confirmed or treated at Memorial Sloan‐Kettering Cancer Center between 1950 and 2000 were reviewed. Patients with vulvar Paget's disease or Bowen's disease were excluded except when Paget's disease of the perianal region was diagnosed first. Whenever possible, follow‐up information was updated. Estimates of overall and disease‐free survival were made by the method of Kaplan and Meier.RESULTS:Twenty‐seven patients with a median age of 63 years were diagnosed with perianal Paget's disease. Most patients (74 percent) were treated with wide excision. Local recurrence occurred in 37 percent of all patients treated and in 30 percent of patients (6/20) undergoing a wide excision as part of their treatment. An invasive component was identified in 44 percent of patients (12/27) with perianal Paget's disease. Six patients (22 percent) required a colostomy as part of the treatment for their disease. Adjuvant chemoradiotherapy was used in 22 percent of patients (6/27) who had more aggressive disease. At a median follow‐up of 67 months, 56 percent (15/27) had no evidence of disease, and two patients had died of metastatic disease. The overall and disease‐free survival at five years was 59 and 64 percent, respectively, which decreased to 33 and 39 percent, respectively, by ten years.CONCLUSIONS:Perianal Paget's disease is a rare finding even at a large referral center. The disease process is generally a prolonged one marked by frequent recurrences, and the treatment of first choice is wide excision. Patients with invasive malignancies require more extensive surgery. The role of chemoradiotherapy remains undefined in this disease.