Multifocal Jejunal Gastrointestinal Stromal Tumor Presenting as Gastrointestinal Bleed in a Patient With Neurofibromatosis Type 1

Abstract

Gastrointestinal stromal tumor (GIST) accounts for only 1% of all gastrointestinal cancers with an incidence of 6 to 15 per one million, despite being the most common mesenchymal tumor of the gastrointestinal tract. Most cases are sporadic, but 5% occur among patients with familial autosomal dominant syndromes like Neurofibromatosis type 1 (NF1). NF1 patients have increased risk for developing gastrointestinal tumors, including rare types like GIST. Only 5% of GISTs in NF1 become symptomatic. This is a rare case of multifocal jejunal GIST in an elderly patient with NF1, presenting as hematochezia. A 61 year old male with NF1, severe coronary artery disease on aspirin and clopidogrel, and history of lower gastrointestinal bleeding from an unknown etiology, presented with one-day history of several episodes of hematochezia. Physical exam was unremarkable except for frank bright red blood mixed with small amounts of melanotic stools on rectal exam, and extensive cutaneous neurofibromas. MRI enterography revealed a proximal jejunum mass. Exploratory laparotomy with small bowel resection was performed. Two dominant lesions in the proximal jejunum and jejunum-ileal junction were noted, but some tumors were not completely excised due to its multifocality. Histology revealed spindle cell neoplasms involving the muscularis propria and serosa of the small intestine, with a low mitosis score. Tumor cells were positive for CD117, and vimentin. Interestingly, our patient had an unremarkable evaluation for hematochezia 3 years prior which included an esophagogastroduodenoscopy, colonoscopy, and capsule endoscopy. Patients with neurofibromatosis type 1 (NF1), an inherited cancer predisposition syndrome due to a mutation in the NF1 gene encoding for neurofibromin, have an increased risk for developing GISTs than general population. It was reported that approximately one third of NF1 patients on autopsy had GIST, and only 5% were symptomatic. Surgical resection is the mainstay of treatment with the chance of cure. However, our patient still had remaining GIST tumors due to its multifocality, and widespread involvement of the small intestine. Treatment of GISTs in NF1 patients is a challenge as these GISTs often lack mutations in KIT and PDGFRA, which causes partial response to Imatinib and other newer tyrosine kinase inhibitors despite their proven success in treatment of sporadic GISTs.Figure: Spindle cell proliferation, bland nuclei, no necrosis, and low proliferative activity.