eP110 - Mesenteric Fibromatosis Presenting as an Irreducible Inguinal Hernia

Purpose/Background: Mesenteric desmoid-type fibromatosis is a rare proliferative disease affecting the mesentery. Although locally-aggressive, it lacks metastatic potential. Local recurrence, however, is common. The common features include: a palpable abdominal mass, bowel obstruction, or ureteral obstruction. The lesion most commonly develops in the abdominal wall and bowel mesentery.Methods/Interventions: The patient is a 67 year-old hypertensive male who presented at the Emergency Department with a three-year history of a gradually-enlarging irreducible left inguinal mass associated with pain and difficulty voiding. He had a soft, nontender, and nondistended abdomen with a 10 x 8 cm irreducible mass at the left inguinoscrotal area. Abdominal CT scan with contrast was done that detected an anterior abdominal wall defect in the left inguinal region, measuring approximately 8 x 5.2 cm containing segments of small bowel, mesenteric fat, and vessels. The patient was brought to the operating room and exploration was done through a left inguinal incision. Conversion to a midline laparotomy became necessary as the mesenteric mass was obscuring the operative field precluding further assessment of the structures. Intraoperative findings revealed a 10 x 13 cm mesenteric mass attached to a segment of ileum 290 cm from the ligament of Treitz that was herniating into the left scrotum. A three-centimeter internal ring was palpated with an empty hernial sac on the left. A segmental ileal resection-anastomosis with mesh hernioplasty on the left was done.Results/Outcomes: The postoperative period was uneventful and the patient was discharged after three days. The histopathology report revealed a spindle cell neoplasm, where immunohistochemistry (IHC) studies with CD117, CD34, S100, SMA, desmin, STAT6 and B-catenin were requested. All the immunohistochemistry panels revealed negative staining except for SMA and B-catenin, which showed diffuse staining in cells of interest. These findings favored a desmoid-type fibromatosis.Conclusion/

Discussion: Mesenteric fibromatosis is a rare abdominal tumor which has a benign behavior. It constitutes approximately 0.03% of all neoplasms. Its incidence in the general population is two to four per million population per year. It usually presents as a sporadic case or after trauma, surgical procedure, or pregnancy.Diagnostic modalities such as computed tomography (CT) or magnetic resonance imaging (MRI) are usually used to define the relationship of the tumor to adjacent structures to assess resectability. The mass can be described as well-circumscribed on gross appearance with varying sizes composed of spindle-shaped cells. Necrosis or hemorrhage and atypia are usually absent. Its origin is usually the small bowel mesentery. On IHCs, dermoid fibromatosis stains positive for nuclear B-catenin, vimentin, cyclooxygenase 2, tyrosine kinase but negative for desmin, S100, CD34 and c-KIT. The beta-catenin signaling pathway plays a key role in the molecular pathogenesis of desmoid tumors. Beta-catenin protein levels are elevated in fibroblasts during the proliferative phase of wound healing and stabilization of intracellular beta-catenin leads to dysregulation of mesenchymal cell proliferation and motility which induces the development of desmoid tumors."Anterior abdominal wall defect detected in the left inguinal region

Representative slide of the anterior abdominal wall defect detected in the left inguinal region, measuring approximately 8 x 5.2 cm (CC x W) seen in the abdominal CT scan with contrast
Ileal mesenteric mass

A 10 x 13 cm mesenteric mass attached to the ileum 290 cm from the ligament of Treitz that herniated into the left scrotum
Beta-catenin

Beta-catenin immunohistochemical panel confirmed the diagnosis of desmoid-type fibromatosis.
SMA

SMA immunohistochemical panel confirmed the diagnosis of desmoid-type fibromatosis. "