Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the gastrointestinal tract, with approximately 5% being located at the rectum. Up to two thirds of GISTs may have a malignant behaviour, with a high recurrence rate.¹

We report a case of a 68 year old woman with multiple local recurrences of a rectal GIST, first operated on 13 years earlier, and who now presented with four adjacent masses located in the rectovaginal septum and no distant metastasis. Molecular analysis identified a 6 bp deletion in exon 11 of the c-kit proto-oncogene. As curative surgery would have implied abdominoperineal resection with permanent colostomy, treatment with imatinib at a standard dose (400 mg/day) was started. Response to treatment was evaluated using endorectal ultrasound and magnetic resonance imaging every three months. Quantification of tumour mass was obtained by adding the products of …