A Huge Pelvic-Abdominal Malignant GIST Tumour in aPatient with Neurofibromatosis Type 1: Case Report andLiterature Review

Gastrointestinal stromal tumours are rare tumours of the gastrointestinal tract (GIT) accounting for 0.1%–3% of all gastrointestinaltumours. The most common location is the stomach (55%) followed by the small bowel (31.8%), colon (6%), other various locations(5.5%), and the oesophagus (0.7%). They may also occur in extraintestinal locations. The signs and symptoms of GIST depend onthe tumour’s location and size. Gastrointestinal bleeding is one of the most common symptoms. Other signs and symptoms includeabdominal discomfort, pain or distention; intestinal obstruction, and weight loss. The association between the development ofGISTs and neurofibromatosis 1 (NF1) has been established. NF1-associated GISTs tend to have a distinct phenotype, and theabsence of KIT/PDGRFαmutations in turn has implications on further management when they do not respond well to imatinibtreatment. Here, we present one of the largest GISTs reported in the literature with a total volume of25:3 × 20 × 14 cm + 27:9×23 × 8 cmand an overall weight of 7.3 kg, which developed in a 43-year-old female patient with NF1 and was resected on anemergency basis due to the rapid deterioration and development of abdominal compartment syndrome. Pathology assessmentshowed a malignant GIST composed of spindle cells with elongated nuclei with necrosis, marked pleomorphism and numerousgiant cell. The mitotic count was>15/50 HPF, Ki 67 was 80%, and the lymphovascular invasion was clear.Immunohistochemistry investigations showed that Vimentin, CD117, and DOG1 were positive, while BCL-2 and CD99 werefocal positives. Pan-CK, S-100, CD34, Desmin, SMA, and HMB-45 were negatives.