e21503 Background: Historically, GISTs were often misdiagnosed as other tumours. However, with the increasing awareness of GISTs, one needs to be careful in confirming the diagnosis since other tumours can simulate GISTs on endoscopy/imaging/histology. We report our 8 year experience of GIST mimics from the CGSG database. Methods: 250 cases discussed in the specialist multidisciplinary meeting from 2004 – 2012 were reviewed. Tumours initially suspected to be GISTs but turned out to be other tumours were included in this analysis. Patient demographics, endoscopic, imaging and histological features were analysed in 41 GIST mimics. Central review by specialist histopathologist was undertaken with immunohistochemical and molecular analysis to differentiate these tumours from GISTs. Results: GIST mimics N= 41. Median age 56 years (range 11 – 82 years), male:female ratio 1:1. Median size 8 cm (range 1.9 – 30 cm). Site of origin of tumours: stomach 34%, oesophagus/junction 15%, mesentery 12%, small bowel 10%, colon 5%, retroperitoneum 5%, pancreas 5%, liver 2% and indeterminate site of origin 12%. Suspicion of GIST was raised from imaging (46%), endoscopy (41%) and histology (39%). The histological subtypes of GIST mimics are summarised in the Table. Conclusions: Many benign and malignant tumours do mimic GISTs on imaging/endoscopy or histology. The diagnosis of GISTs should be made by a specialist multidisciplinary team with experience in imaging and histopathology. Distinguishing GISTs from their mimics is of critical importance both for prognosis and management. [Table: see text]
Conditional crude probabilities of death for English cancer patients
