Large Desmoid Tumor Presenting With Abdominal Pain

Abstract

Desmoid tumors are firm, infiltrative and locally aggressive fibrous neoplasms that have no known potential for metastasis but can cause local recurrence. They are rare, accounting for 0.03% of all neoplasms. However the risk is increased with familial adenomatous polyposis(FAP). A 31 year-old male with no significant past medical history presented with a three to four month history of progressive weight loss and abdominal distention. He deniednausea, diarrhea, decreased oral intake, constipation, melena, hematochezia, hematuria, decreased urine output, fever, chills or night sweats. Physical exam revealed a smooth, firm, non-pulsatile, periumbilical mass that was 20 cm in diameter and not freely moveable. Laboratory studies were normal. Computed tomography showed a large, bulky anterior abdominal mass extending from the sella gastric region into the pelvis. It extended over a craniocaudal length of about 29 cm and measured approximately 22.4 by 11.7 cm in diameter. The lesion compressed the right and left colon posteriorly into the paracolic gutters and the inferior vena cava was markedly compressed. He subsequently underwent exploratory laparotomy to resect the mass. A 30 cm by 20 cm by 15 cm mass was found attached to body of the pancreas, transverse colon, and greater curvature of the stomach. Since the mass was locally infiltrative, he required a partial colectomy, subtotal pancreatectomy, partial gastrectomy, cholecystectomy and splenectomy. Pathology showed desmoid fibromatosis with adhesion to the stomach and infiltration into the pancreas as well as the outer colonic wall. Surgical margins were negative for tumor. There were no polyps involving the resected colon. Immunohistochemistry showed nuclear positivity for beta-catenin and patchy positivity for desmin with focal positivity for smooth muscle actin also seen. The patient recovered from his surgery and was subsequently discharged from the hospital with oncology follow up. The risk of desmoid tum or is increased in patients with FAP, with a prevalence as high as 13%. Patients typically present with slow growing masses in the anterior abdominal wall and shoulder girdle. A history of trauma at the site of the tumor, including previous surgery, has been associated with desmoid tumors. Surgical resection with negative margins is the most successful approach in treatment, including patients with FAP. Radiation therapy can be considered for patients that are not surgical candidates.1505_A Figure 1. The abdominal mass has an overall measurement of 35.0 x 31.0 x 11.5 cm. The mass showed desmoid fibromatosis with adhesion to the stomach and infiltration into the pancreas as well as the outer colonic wall. The spleen is also seen attached. Surgical margins were negative for tumor.1505_B Figure 2. Tumor shows nuclear positivity for Beta-catenin and patchy positivity for desmin with focal positivity for smooth muscle actin also seen.