Introduction: Desmoid tumors are rare, monoclonal, fibroblastic proliferations that arise in deep soft tissue. These tumors are benign with no metastatic potential; however, they are locally invasive with high recurrence rates. Desmoid tumors are driven by alterations of the Wnt/APC/β-catenin pathway. Sporadic desmoids tumors comprise the majority, 85-90%, and are associated with somatic mutations of CTNNB1. Approximately 10-15% are associated with germline APC mutations in the familial adenomatous polyposis (FAP) syndrome. These tumors make up <3% of soft tissue sarcomas and about 0.03% of all malignancies. Desmoid tumors can arise in any anatomic location, but tend to arise in the extremities, joints, and abdomen. Clinical symptoms vary depending on the location. The treatment of desmoid tumors requires an individualized approach.

Case Presentation: We present a case of a 64 year old male who was experiencing intermittent mid-abdominal pain. The pain was described as crampy gas pains. He experienced this pain 3 days prior which resolved spontaneously, and was similar to a previous episode he had 5 years ago. The patient was hospitalized at that time and was found to have a mesenteric mass on CT. He deferred diagnostic laparoscopy then and was discharged when symptoms improved. This hospital course consisted of a CT Abdomen/Pelvis which revealed a partial small bowel obstruction, as well as a slight increase in size of the mesenteric mass now measuring 3.0 x 2.8 cm. The patient was managed conservatively and he was discharged after he had a return of normal bowel function. He agreed to follow up outpatient with general surgery.

Working Diagnosis: Outpatient NM/PET scan showed no significant hypermetabolic activity associated with the mesenteric mass, and the chronicity of the lesion could suggest a low-grade malignancy. Intra abdominal biopsy of the mass was deferred due to the location and potential for complications. A diagnostic laporoscopy was planned with resection of the mesenteric mass.

Management & Outcome: The diagnostic laporoscopy was converted intraoperatively to an exploratory laparotomy. A mass of small bowel was identified which was wrapped around its mesentery. Within the mesentery, a small circular mass could be felt. The small bowel mass and mesenteric mass were resected and a subsequent small bowel anastomosis was completed. Pathology findings revealed a densely collagenous hypocellular tumor consistent with a desmoid tumor. The post-op course was uneventful and the patient was discharged on post-op day 4.This case exemplifies the difficulty in diagnosis and treatment of desmoid tumors, specifically those that are intra-abdominal. Diagnostic steps should include a histologic confirmation if it’s safe to conduct. When it comes to treatment, there is consensus on a “watch and wait strategy” for newly diagnosed patients with non-life threatening symptoms. When deciding between an active or definitive treatment; the initial tumor size, growth rate, location of the tumor, its risk to organs or nerves or worsening of function, should be weighed. Surgical resection is the recommended treatment for operable intra-abdominal desmoid tumors.