ROS1-positive Inflammatory Myofibroblastic Tumor of the Small Bowel Causing Obstruction: A Case Report.

Inflammatory Myofibroblastic Tumors (IMTs) are rare fibroblastic/myofibroblastic neoplasms that affect predominately pediatric patients and young adults. Almost half of the patients with IMTs have a chromosomal abnormality in the Anaplastic Lymphoma Kinase 1 gene on chromosome 2p23. Although these tumors occur primarily in the lung, lesions have been reported in a variety of intra-abdominal organs like the liver, spleen, and mesentery. Small bowel IMTs are particularly rare. IMTs generally pursue a benign clinical course, however intra-abdominal and retroperitoneal tumors have typically shown higher local recurrence and even distant metastases. The most common presenting symptoms of an intra-abdominal IMT are abdominal pain and change in bowel habits. Laboratory results are nonspecific and can include anemia and minor elevation of inflammatory markers like C-reactive protein. We report an unusual case of IMT in the small bowel causing the obstruction.