Elobu Alex E. et al.; International Journal of Advance Research, Ideas and Innovations in Technology © 2019, www.IJARIIT.com All Rights Reserved Page |1813 ISSN: 2454-132X Impact factor: 4.295 (Volume 5, Issue 3) Available online at: www.ijariit.com Mesenteric fibromatosis mimicking GIST and presenting as a rare cause intestinal obstruction in a 1 year old boy: A rare case report Alex E. Elobu alex.elobu@iddstar.org Fortis Hospital, Mulund, Mumbai, Maharashtra Vianney Kweyamba kwevan@gmail.com Fortis Hospital, Mulund, Mumbai, Maharashtra Ushma Wartikar ushma.wartikar@srl.in Fortis Hospital, Mulund, Mumbai, Maharashtra Brijesh Kumar brijesh.kumar@srl.in Fortis Hospital, Mulund, Mumbai, Maharashtra Rakesh Rai raisvasti@gmail.com Fortis Hospital, Mulund, Mumbai, Maharashtra ABSTRACT Mesenteric Fibromatosis (MF) is a rare myofibroproliferative tumour that may present as a common clinical entity like intestinal obstruction or abdominal mass. They are exceedingly rare in the pediatric population. They often mimic Gastrointestinal Stroma Tumours (GIST) in their presentation, imaging and even histological features. Here we present the case of a one year, 9 months old boy who had a right hemicolectomy for an obstructing ascending colon tumour whose initial histological analysis was suggestive of GIST. A repeat analysis including Immunohistochemistry staining confirmed the diagnosis of MF. No further treatment was given and the child is asymptomatic one year later. MF though rare may present as common clinical entities and tends to mimic MF. Detailed analysis is required to distinguish it from GIST as the prognosis and treatment may differ significantly. Keywords— Mesenteric fibromatosis, Gastrointestinal stromal tumour, Intestinal obstruction 1. BACKGROUND Mesenteric Fibromatosis (MF) belongs to a spectrum of rare tumours called Desmoid Tumours (DT) that occur in 2-4 cases per million population. They account for 0.03% of all tumours and 3% of all soft tissue tumours. DTs are myofibroblastic proliferative and infiltrative tumours that lack metastatic potential. MF is the commonest of these otherwise rare intra-abdominal desmoid tumours [1]. Although generally rare, these mesenteric fibromatoses may present as common clinical entities e.g. abdominal mass or intestinal obstruction thus presenting a diagnostic dilemma in these situations. They are very rare in the paediatric age group [2]. They often mimic the more common Gastro-Intestinal Stromal Tumours (GIST) in clinical presentation, imaging findings and even histology [3] . It is important to distinguish MF from GIST because there is a distinct difference in their prognosis and several aspects of their management. Here, we present a rare case of intestinal obstruction caused by MF in a one year old boy, which was initially diagnosed as GIST. 2. CASE PRESENTATION A 1 year, 9 months old boy of African origin presented at the age of 1 year and 3 months with features of intestinal obstruction at a hospital in his home country. He underwent an exploratory laparotomy in which an obstructing ascending colonic tumour was discovered and a right hemicolectomy was performed. This led to resolution of symptoms and the patient was discharged in good condition after an uneventful post-operative hospital stay. Five months later, he presented with features of intestinal obstruction similar to the previous episode. An exploratory laparotomy was performed but it did not identify any obvious mechanical obstruction. The patient was then referred to our institution for further assessment with a clinical and histopathological diagnosis of GIST. He was stabilized and investigated. An abdominopelvic CT scan revealed dilated loops of small bowel with air fluid levels but no obvious transition or mass lesion seen. The patient was managed non-operatively with a resolution of the obstructive symptoms and later discharged in stable condition.