Abstract

We present a 70-year-old man with chronic pilonidal sinus. Inflammation had worsened in previous months and exploration revealed a large ulcerative mass which biopsy showed a squamous cell carcinoma. CT scan and MRI imaging showed tumoral invasion of the coccyx and both gluteus major muscles. Neoadjuvant radiotherapy, chemotherapy as radiosensitizer and surgery with intraoperative radiotherapy was decided in the multidisciplinary tumor committee. Post neoadjuvant therapy MRI showed partial response with a  decrease of the mass but persistence of the coccyx infiltration.