Obscure Gastrointestinal Bleeding in a Patient With Neurofibromatosis Type 1

Abstract

Neurofibromatosis Type 1 (NF1) is an autosomal dominant disorder affecting approximately 1 in 3000, with well-known skin, ocular, and CNS manifestations. Gastrointestinal (GI) abnormalities are reported in 5-25% of cases of NF1. They may, however, go unrecognized as only 5% of these abnormalities are symptomatic. In particular, gastrointestinal stromal tumors (GIST) appear associated with NF1. GIST tumors account for less than 1-3% of all GI malignancies, but are the most common GI manifestation of NF1. We report a case of obscure GI bleeding for 7 years with eventual discovery of a small bowel GIST in a patient with NF1. A 39-year-old male with NF1 was transferred to our hospital with melena and hematochezia. He reported several episodes of GI bleeding since 2007 and required previous transfusions for chronic anemia. Extensive workup had been negative, including CT enterography, Meckel's scan, colonoscopy, EGD and capsule endoscopy. On admission, his hemoglobin was 6.0g/L, yet he was hemodynamically stable. Physical examination revealed mild epigastric pain and neurofibromas of his back. He was admitted to the ICU on a pantoprazole drip and received RBC transfusions. A tagged RBC scan localized bleeding in the duodenum/jejunum. Subsequent small bowel enteroscopy located a 4 cm ulcerated submucosal mass in the proximal jejunum with active bleeding. He then underwent partial small bowel resection with primary anastomosis. Pathology was positive for a low grade GIST (stage T3), characterized by a low mitotic index, with negative margins and lymph nodes. The patient did well post-operatively and his hemoglobin stabilized at 9.0g/L by discharge. He was then lost to follow-up. In NF1, mutation of the NF1 tumor suppressor gene on chromosome 17 leads to loss of tumor suppressor function and subsequent development of benign and malignant tumors. NF1-associated GI findings include neurogenic neoplasms, neuroendocrine tumors, and most commonly GIST. The majority of NF1-associated GISTs are small asymptomatic lesions with low malignant potential, often noted incidentally on imaging. Intermittent GI bleeding and anemia over several years are the most common presentations. Treatment for NF1 GIST includes surgical excision of localized tumor with good prognosis. For large tumor burden, few studies have reported cytoreduction with tyrosine kinase inhibition prior to surgical excision, but describe variable results.