Mesenteric Fibromatosis any complications. The patient is attending follow-ups and shows no signs of abnormality or recurrence. DISCUSSION Fibromatosis can affect both superficial and deep parts of the body. Superficial fibromatosis can involve the face, neck, palms, feet, penis, shoulder, thigh, buttocks, or trunk. The deep variant can involve the abdominal wall, mesentery, retroperitoneum, mediastinum, or abdominal cavity. MF is an uncommon variant of deep fibromatosis and has only occasionally been reported [3]. Deep (or aggressive) fibro- matosis is sometimes referred to as a desmoid tumor. A des- moid tumor is a very rare tumor that may or may not be part of a hereditary disease such as familial adenomatous polyposis. MF is a rare subtype involving the bowel mesen- tery (especially that of the small bowel) or retroperitoneum and comprises only 8% of all desmoid tumors [4]. Less com- mon locations are the mesocolon and omentum [2]. The ex- act etiology of these lesions remains elusive. Various fac- tors have been implicated by different researchers. Trauma, including previous surgery and estrogen exposure, may contribute to the formation of these tumors [5]. Genetic pre- disposition also plays a role, and patients with Gardner’s syndrome have a much higher incidence of intra-abdomi- nal fibromatosis. Although one-third of patients with Gardner’s syndrome will have a desmoid tumor, only 2% of patients presenting with a desmoid tumor will be found to have Gardner’s syndrome [6]. An infectious etiology is suggested by an association between human herpes virus and retroperitoneal fibromatosis in macaque monkeys [5]. The present case is peculiar in that MF presented in a wom- an without any of these factors. 　Most patients are clinically asymptomatic, with little or no focal symptoms until later in the course of the disease, at which time they complain of pain, discomfort, con- stipation, vomiting, abdominal mass, weight loss, and symptoms due to organ compression [4]. Some complica- tions that have been reported include small bowel ob- struction and hydronephrosis [4]. In our case, the patient had intermittent right abdominal pain for a year, but there were no other symptoms, such as weight loss, emesis or a palpable mass. 　Radiologically, metastatic carcinoma, abdominal lym- phoma, intestinal carcinoids, peritoneal neoplasms, post- operative adhesions and retractile mesenteritis form the differential diagnoses [3]. A combination of CT for primary diagnosis and image-guided biopsies and magnetic reso- nance imaging (MRI) for periodic follow-up would be rec- ommended in such patients, as both modalities have a large field of view and multiplanar and vascular imaging capa- bilities. Typical pathological features of MF include a well- circumscribed mass, often firmly attached to the small bowel; less often MF presents as an ill-defined and irregu- lar mass. One study reported that the cut surface was a glis- tening pinkish-white in color and whorled. Histology re- vealed well-differentiated fibroblasts of uniform size with 503 no evidence of mitotic activity, although there was infiltra- tion of the surrounding tissue. Inflammatory infiltration was notably absent [3]. The pathologic confirmation of our case and the typical features of MF did not differ. 　In confirming the pathologic diagnosis of MF, it can be difficult to distinguish MF from sclerosing mesenteritis that appears to be related to mesenteric panniculitis and mesenteric lipodystrophy. In such a case, immunohisto- chemical staining for beta-catenin can be useful, since MF consistently shows strong nuclear beta-catenin staining, whereas sclerosing mesenteritis does not express this anti- gen [7]. Distinguishing MF from gastrointestinal stromal tumors (GIST) of the mesentery is also of clinical sig- nificance due to their vastly different therapeutic and prog- nostic implications. Although the histopathologic features of MF and GIST can sometimes be confused, a differential diagnosis between MF and GIST can be carried out using immunohistochemical staining. In some studies, CD34 was common in GIST but was not detected in MF, and MF was consistently negative for KIT (CD117), whereas GIST was commonly positive. Nuclear beta-catenin staining characteristic of MF (but absent in GIST) is also a useful finding [7]. SMA, Desmin, and S-100 were not useful for dis- tinguishing MF from GIST or sclerosing mesenteritis in previous studies [7]. 　Surgical excision remains the mainstay of MF therapy, with non-surgical modalities assuming a secondary role as high recurrence rates have been reported when surgery is used alone [5]. Indeed, it has been suggested that a re- currence could be caused by the surgical trauma itself. From the literature, it is evident that no single method of treatment is effective. The high recurrence rates after sur- gical excision may reflect the diffuse infiltrative growth pattern of desmoid tumors. As many mesenteric fibroma- toses are unresectable because of their location and extent and because they are a cause of morbidity at the same time, alternative modes of therapy frequently become the pri- mary treatment, to be followed by surgery if the tumor shrinks to within the limits of resection. Non-surgical mo- dalities have also been used to reduce the recurrence rate. The use of hormonal therapy (i.e., tamoxifen), nonsteroidal anti-inflammatory drugs, and interferon as well as sys- temic chemotherapy may play an important role in the treat- ment of MF [8]. Post-operative radiation therapy is recom- mended and is often used for positive margins identified histologically, but its role is controversial [5]. In stable tu- mors and in those that diminish in size, no treatment may be necessary. Prognosis is good after complete excision. Local recurrences must also be treated by excision. A re- sidual tumor left behind after surgery takes several years to spread before a second exploration is warranted. Subsequent surgery, however, is difficult due to extensive intraperitoneal adhesions created by previous surgical procedures. With each subsequent surgery, morbidity and mortality increase [3]. Extensive involvement of the ab- dominal viscera is the ultimate cause of death after several years [3]. Korean J Urol 2010;51:501-504