Aggressive Angiomyxoma (AA) is a soft tissue tumour that principally affects women of the reproductive age, primarily involving the pelvis and the perineum. Despite being slow growing, it is classified as aggressive due to its locally infiltrative nature and high recurrence. It is rare, often asymptomatic and is misdiagnosed. However, it has characteristic features on radiographic imaging. Complete surgical resection is the ideal approach to treat AA. We report a case of an aggressive angiomyxoma in a 17 year old female, located in the ischiorectal fossa and diagnosed incidentally on a magnetic resonance imaging (MRI). The lesion was excised without complication.