Abstract
A case of adenocarcinoma growing in the subcutis of the perianal region is reported. A 66-year-old man showed a symptom of subcutaneous induration. Histological evaluation after preoperative biopsy revealed adenocarcinoma. Based on a preoperative diagnosis of rectal cancer, the patient underwent abdominoperineal resection, partial resection of the gluteal muscle, lateral lymphnode dissection and right inguinal lymphnode dissection. Histological examination of the resected specimens revealed no abnormalities in the rectal mucous membrane and epithelium of the anal canal. There was no connection between the anal gland and the tumor. Moreover, in pathological and biochemical examination using PATS/PBT/KOH/PAS staining, the tumor was found to have originated not in the anal gland but rather in the rectal mucous membrane. These results suggest that in the initial stage of development, a portion of the hindgut had intruded the subcutis in the perianal region and had later become cancerous.
