A Fibromatosis Case Mimicking Abdominal Aorta Aneurysm

Retroperitoneal fibrosis is a rare fibrosing reactive process that may be confused with mesenteric fibromatosis. Abdominal aorta aneurysm is rare too and mostly develops secondary to Behcet’s disease, trauma, and infection or connective tissue diseases. Incidence of aneurysms occurring as a result of atherosclerotic changes increases in postmenopausal period. Diagnosis can be established with arteriography, tomography, or magnetic resonance imaging associated with clinical findings. Tumors and cysts should be considered in differential diagnosis. Abdominal ultrasound and contrast-enhanced computerized tomography revealed an infrarenal abdominal aorta aneurysm in a 41-year-old woman, but, on surgery, retroperitoneal fibrosis surrounding the aorta was detected. We present this interesting case because retroperitoneal fibrosis encircling the abdominal aorta can mimic abdominal aorta aneurysm radiologically. 1. Introduction Retroperitoneal fibrosis is a rare reactive process. It is two to three times more common in men, and most patients present with it during the fifth or sixth decade of life [1]. It is unusual before the age of 20 or over the age of 70. It is characterized by diffuse or localized fibroblastic proliferation in the retroperitoneum causing compression or obstruction of the ureters, aorta, or other vascular structures. Abdominal aorta aneurysms (AAAs) are vascular pathologies that mostly develop in advanced-age group due to atherosclerosis. AAAs have a male predominance. But following menopause, female/male ratio becomes equal. Aneurysms become symptomatic after they reach a certain diameter. The diagnosis is established radiologically. But sometimes, benign or malignant lesions may mimic AAAs by surrounding the aorta. Herein, we report a 41-year-old woman who had complaints of abdominal and back pain and was diagnosed as AAA on CT and USG. But on surgery, it was seen that the periaortic thickening was due to retroperitoneal fibrosis. Therefore, we aimed to present this rare case and stress that retroperitoneal fibromatosis should be kept in mind in the differential diagnosis of AAA. 2. Case Report A 41-year-old woman was admitted to the cardiology clinic because of abdominal and back pain. Physical examination revealed a mass in the subxyphoideal region. An abdominal aorta aneurysm with thrombosis was detected on abdominal ultrasound. CT was obtained for showing the extent of the lesion. CT showed an infrarenal aneurysm (Figure 1) that extends through terminal aorta under renal arteries and reaches to a diameter of 6？cm in some areas. Blood