A Rare Case of Inflammatory Myofibroblastic Tumor Mimicking Fibrous Adhesions Resulting in Bowel Obstruction

Abstract

Inflammatory myofibroblastic tumor (IMT) is a rare mesenchymal tumors of unknown etiology composed of myofibroblastic cells admixed with inflammatory cells. Presented is a 72-year-old male hospitalized for severe abdominal pain and hematochezia with onset of associated symptoms of fever and sweats a few hours prior to abdominal pain. A computed tomography (CT) demonstrated left colonic thickening interpreted as partial obstruction, gross adhesions, and ischemia. At surgery, marked bowel ischemia from the distal transverse to proximal sigmoid colon was seen with extensive gross adhesions. Histopathology revealed a mesenteric mass chiefly composed of stellate-to-spindled myofibroblastic cells and fibrous adhesions, intermixed with lymphocytes, histiocytes, and plasma cells. The tumor was positive for desmin, smooth muscle actin, and keratin; tumor staging, grade, and postsurgical follow-up were not completed as the patient expired postoperatively. Illustrated is a rare pathologic mimic of ischemic colitis with fibrous adhesions, IMT. Thus, it should not be assumed that fibrous adhesions are always the etiology of obstruction when "adhesions" between sections of bowel are noted radiologically or surgically.

Keywords: bowel obstruction; inflammatory myofibroblastic tumor; ischemic colitis; mesenteric mass.

Figure 1

CT scan with normal proximal colon wall thickness (1). Distal transverse colon and proximal descending colon wall thickening and hypoenhancement suspicious for ischemic colitis (2). Point of partial colon obstruction and no visible obstructive colon, omental, or mesenteric mass (3). CT, computed tomography.

Figure 2

Myofibroblastic cellular proliferation with associated variable fibrosis and intermixed lymphocytes, histocytes, and plasma cells, noted by arrows, infiltrating into the muscularis propria of the colon, noted by the star. Note how the muscularis propria is clearly distinct from the myofibroblastic infiltration (H&E 2x). H&E, hematoxylin and eosin.

Figure 3

Myofibroblastic cellular proliferation involving the serosa and subserosa of the small bowel denoted by arrows abutting the univolved muscular propria annotated by a star (H&E 2x). H&E, hematoxylin and eosin.

Figure 4

(A) Variable keratin AE1/AE3 positivity in the myofibroblastic proliferation (10x). (B) Variable desmin positivity in the myofibroblastic proliferation (10x). (C) Strong smooth muscle actin positivity in the myofibroblastic proliferation (10x).