Giant Cell Tumor of Acl Tendon Sheath

INTRODUCTION The Giant Cells Tumor of Tendon Sheath (GCTTS) is a histiocyte-simile benign tumor associated to multinucleated giant cells, taking circumscribed or polygonal shapes(1), with sizes ranging from 0.5 to 5.5cm(2,3). Its etiology is not fully understood yet(4). It is more commonly found on hands and feet, and more rarely on ankles and knees(1,5). The GCTTS affects individuals at the age of 46 in average (6 – 71 years) and is more frequently found in women 1,6M:1H. Its annual incidence, according to Monaghan et.al is 1/50,000(4). GCTTS localized at the knee corresponds to 2.8 – 3.9% of the total number of occurrences. In the knee, the most common sites are the suprapatelar recesses and the medial meniscal-capsular union(6). Clinical manifestations are unspecific and include: complaints of pain and diffuse swelling, which can affect the range of movement of the involved(7). X-ray images do not present specific findings(8), with NMR being the most accurate method for preoperative diagnosis(9). The arthroscopic treatment has been shown to be effective, presenting low morbidity, and being clinically resolving(7). The objective of this study is to report a GCTTS case on the Anterior Cruciate Ligament, a rare tumor, in a further rare site for this kind of lesion.