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  • br Conclusion br Conflict of interest


    Conflict of interest
    Introduction Giant cell tumor (GCT) is a primary intramedullary bone tumor that is composed of mononuclear and giant mononuclear cells, resembling Tasquinimod [1]. It usually involves the end of a long bone. The World Health Organization has classified GCT as an aggressive, potentially malignant lesion [2]. GCT accounts for 3–8% of primary bone tumors in Western nations, but it is more common in Asia, accounting for 20% of primary bone tumors [3–8]. GCT is most commonly diagnosed among 20–40 year olds, more likely to locate many sites of body, but half of GCTs occur around the knee [3,4,9–12]. About 10% of GCTs undergo malignant transformation, and pulmonary metastases occur in 1% to 4% of cases [13]. It has been reported that the postoperative recurrence rate is 10%–65% [5,6,14–16]. Therefore, GCT is one of the most controversial and widely discussed bone tumors [1,17,18]. Previous, large retrospective studies from a single institution have indicated that GCTs predominantly occur among women, with a male-to-female gender ratio of 0.8:1 [5,19,20]. However, some studies have not shown this predominance [1,17,18]. Further, other studies have shown that most cases in Asia occur in men, with a gender ratio of 1.27–1.77 [21–24].
    Materials and methods
    Discussion The incidence rates and gender distributions of GCT have become issues of contention for researchers around the world. In a study in the US city of Philadelphia, it was determined that GCT accounts for 5–7% of all primary bone tumors, yet it has also been reported that GCT accounts for 30% of primary bone tumors in south India [22]. In Western nations, GCT is more likely to occur in women than in men; one study has reported that 48.5% of cases occur in men and 51.5% occur in women [20], while another study has reported that 44% of cases occur in men and 56% occur in women [28]. However, several studies have reported that GCT predominately occurs in men, with a male-to-female gender ratio of 1.27–1.77 [7,21–23]. Consistent with these studies, we also found that first GCT around the knee predominantly occurred in men, with a gender ratio of 1.14:1 in the present study. Most studies have indicated that GCT usually occurs in young adults aged 20–40 years, accounting for 70–80% of all cases, and that few cases occur after epiphysis clogging [20,28]. In the present study, 77.8% patients with primary GCT around the knee were diagnosed at the age between 20–40 years. Moreover, we found that first GCT around the knee was diagnosed at a younger average age in women than in men; this may be explained by earlier epiphysis clogging in women. Studies of the laterality of GCTs of the knee are rare, though all studies have confirmed that the knee is the joint that is the most common site for this disease, accounting for 50–70% of cases [6,7]. In this study, a higher prevalence of first GCT was observed for the right knee in the group of patients ≤40 years of age. This may partly be explained by dextrality and heavy load bearing in young adults. The prevalence of eccentric growth was dominant in this study, a finding that is consistent with previous studies [7]. Campanacci et al. reported that only 10–15% of GCTs belong to grade I [29]. The most common grades were II and III, accounting for 70–80% and 20% of cases, respectively [28]. In contrast with these previous studies, we found similar prevalence rates of grade II (44.9%) and grade III (44.0%) disease in the present study. In several studies, it has been reported that grade III has a high recurrence rate [6,26,30]. However, results from China suggest higher recurrence of GCT with Campanacci grade II [7]. Thus, treatment of GCT should simultaneously focus on local control and the maintenance of function. We found a greater prevalence of Enneking stage T2 stage in patients aged >40 years (35.0%) than in patients aged ≤40 years (18.6%).