Giant rectal gastrointestinal stromal tumours: a diagnostic and therapeutic challenge
An elderly man in his seventies presented to the Urology department with two episodes of acute urinary retention. There were no rectal symptoms and rectal examination revealed an enlarged prostate. He underwent a laser transurethral resection of prostate during which a large palpable pelvic mass was noted. The subsequent urgent MR pelvis revealed a large tumour in the mesorectum arising from the anterior rectum 10 × 8.5 cm (Figs and ). A transrectal ultrasound and biopsy were performed; histology revealed a spindle cell tumour, with positive immunostains for CD117 and DOG1 with 5 mitoses per 50 high power fields. This was confirmed to be a locally advanced high-risk GIST.\nThe multidisciplinary team review advised neoadjuvant treatment with imatinib mesylate and further reassessment. Repeat MR pelvis and staging PET CT abdomen, thorax and pelvis were then performed. These showed a large extra-luminal tumour with downsizing in tumour bulk (6 × 5.7 × 5.4 cm) (Figs –) but in close approximation with the right seminal vesicle.\nFurther examination under anaesthesia, flexible sigmoidoscopy and cystoscopy were performed. The tumour was a large right-sided mass with no prostatic involvement. An elective Hartmann's procedure plus possible pelvic clearance was organized. Intraoperatively a large tumour in close proximity to the posterior bladder and seminal vesicles was found. Although there was no evidence of invasion, dissection of the plane between the GIST and posterior bladder was not possible, thus cystectomy and prostatectomy were performed with an ileal conduit and urostomy. The sigmoid colon and rectum were resected leaving an end colostomy as planned. In the postoperative period the patient developed signs of sepsis. A subsequent CT revealed an anastomotic leak at the ileo-ileal site. The patient returned to theatre, the anastomosis was taken down and a double barrel ileostomy sited. He initially went on to recover well. Operative histology revealed reduced mitotic activity and downgrading of tumour activity with clear R0 resection margins.