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Received Jun 15, 2017; Revised Nov 28, 2017; Accepted Dec 27, 2017
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1. Introduction
Desmoid-type fibromatosis is a benign fibrous neoplasia originating from connective tissue, fascial planes, and musculoaponeurotic structures of the muscles [1]. This tumor is not capsulated and usually infiltrates along fascial planes and invades adjacent neurovascular structures [2]. In 1832, McFarlane was the first to describe a case, and six years later, Muller coined the term “desmoid tumor,” derived from desmos which means tendon-like in Greek [3, 4]. This tumor is extremely rare, and the incidence of desmoid fibromatosis is 2 to 4 per 1 million per year with a female-to-male ratio of 3 to 1 [5–8]; it represents less than 3% of all soft tissue sarcomas [9]. The disease can be divided into two groups because desmoid fibromatosis can be sporadic or associated with a hereditary syndrome. In both groups, there is a genetic predisposition [8]. The incidence of desmoid fibromatosis is remarkably higher in patients affected by familial adenomatous polyposis and Gardner syndrome [10]. In these cases, the disease is usually intra-abdominal. Another described hereditary syndrome involved is the autosomaldominant inheritance of familial infiltrative fibromatosis [11]. In the familial adenomatous polyposis, Gardner syndrome, and familial infiltrative fibromatosis, lesions are associated with the inactivation of the APC tumor suppressor [6, 12]. In the sporadic desmoid fibromatosis, more than 60% of tumors contain mutations in CTNNB1 (the gene that codes for beta-catenin) [12] with p.T41A (threonine to alanine), p.S45F (serine to phenylalanine), and p.S45P (serine to proline) being the most frequent [13, 14]. Desmoid fibromatosis is derived from mesenchymal stem cells in the deep soft tissues, and mutations of beta-catenin can support tumorigenesis causing resistence to the inhibitory influence of APC and maintaining mesenchymal progenitor cells in a less differentiated state [6, 12]. Accumulation of beta-catenin can be detected using immunochemistry, but limitations have been acknowleged in this diagnostic procedure [13]. Abdominal desmoid fibromatosis is slightly more frequent than extra-abdominal desmoid fibromatosis [7]. Predilected sites of the extra-abdominal desmoid fibromatosis are the shoulder, chest wall and back, thigh, and head and...