A Case of Abdominal Desmoid Tumor Suspected of Malignancy

Abstract

A 78-year-old man was referred to our hospital with the complaint of abdominal distention. He had undergone laparotomies for gastric cancer surgery and surgery for cholecystolithiasis, and had been followed up for incisional hernia at another hospital. Abdominal CT obtained the previous year showed a solid mass measuring 3 cm in diameter, however, the patient chose only to be followed up. However, the mass rapidly grew in size at the margin of the incisional hernia, reaching 11 cm in diameter. ¹⁸F-fluorodeoxy glucose positron emission tomography (FDG-PET) revealed high ¹⁸F-FDG uptake in the mass (standard uptake value: SUV max 4.6 at one hour, and 6.2 at two hours after ¹⁸F-FDG injection). We suspected a malignant tumor, such as intestinal GIST or disseminated gastric carcinoma, because of the rapid growth and high ¹⁸F-FDG uptake of the tumor. Under informed consent, we performed tumor resection with the adjacent abdominal wall and reconstructed the abdominal wall using an artificial mesh. Histological examination of the tumor revealed a desmoid tumor. In this case, because the tumor rapidly grew and FDG-PET revealed increasing ¹⁸F-FDG uptake with time, it was difficult to determine if the tumor was malignant or benign.