Mystery Behind Hidden Long Standing Perianal Fistula-mucinous Adenocarcinoma

Mucinous adenocarcinomas (MA) of the perianal region is a rare entity and have an uncertain etiopathogenesis. They are mostly contributed by, or MA arising from chronic perianal fistula (PF) has an indolent growth with locoregional spread, and increased rate of disease recurrence. Here, we report a rare case of a 58-year-old male presenting with MA of a left perianal exophytic growth for 20 years and hidden PF tract. Though abdomino-perineal resection remains mainstay of treatment, we were able to achieve effective response by doing wide local excision of malignant lesion with fistulous tract and primary reconstruction of the defect by V-Y flap and adjuvant chemotherapy.