Fig. 16

A 39-year-old woman with history of ulcerative colitis and perianal inflammation. Initial multiplanar MDCT (a, b) identified enhancing anal thickening (arrowheads) with right-sided vaginal infiltration and solid tissue (*) extending to reach the internal obturator muscle. After biopsy confirmation of SCAC and surgical debulking with colostomy, repeat MDCT (c, d) detected enlarging neoplastic residue (*). Shortly after chemo-radiotherapy, MRI (e) detected the formation of a thick hypointense fibrotic band in the site of the regressed tumour (thin arrows). MRI follow-up (e) identified appearance of a contralateral enhancing tissue band interpreted as suspicious for local recurrence (arrow). After negative clinical reassessment and PET findings, this post-treatment finding remained stable on further MRI studies (not shown)