Malignant peripheral nerve sheath tumour in the ischio-rectal fossa.

Primary sarcomas in the ischiorectal fossa are occasionally reported and represent a significant challenge due to the proximity of rectum, levator muscles and pudendal neurovascular structures. We report a case in which the diagnosis changed between biopsy (desmoid tumour) and resection (malignant peripheral nerve sheath tumour), requiring a multidisciplinary surgical approach involving different sub-specialties. It also illustrates the importance of undertaking sarcoma surgery in a recognized sarcoma centre with sarcoma expertise available across a range of disciplines.