Anahtar KelimelerDev Hücreli Tendon Kılıfı Tümörleri; Parmak; MR Görüntüleme; Cerrahi; Direk Grafi Abstract Aim: The aims of this retrospective study were to evaluate localized giant cell tumors of the tendon sheath (GCTTS) with Magnetic Resonance (MR) imaging findings and to review the epidemiological features of the disease. We also evaluated the literature regarding GCTTS and performed an analysis of the available information. Material and Method: We retrospectively reviewed the MR images of 25 histologically proven cases of GCTTS of the finger during the period between 2012-2014. In addition, a retrospective analysis of the patients' records was carried out, and age, gender, site and size of lesion, recurrence, and MRI findings were reviewed. Results: The patients were predominantly female (n = 16) and had a mean age of 51.9 ± 12.8 years. Nine patients were male with a mean age of 45.1 ± 13.4 years. The size of the tumors ranged from 6 mm to 30 mm, with a mean size of 15.3±6.8 mm. Tumors were present on the right hand in 15 patients and on the left hand in 10 patients. Among women, 11 tumors were located on the right hand and 5 were found on the left. In men, 4 of the tumors were located on the right hand and 5 were on the left. The most frequent digit on which tumors were found was the index finger, accounting for 40% of cases (n=10). The most frequent location was the index finger for both women (n=6) and men (n=4). All of the lesions were described as well-circumscribed, encapsulated, lobulated, or multilobulated solitary masses with MR imaging. Signal intensity on T1 weighted images (WI) was equal to that of skeletal muscle in 23 cases. In two cases, signal intensity was slightly higher. On T2WIs, the signal intensities tended to be between those of skeletal muscle and fat in all of the cases. All of the lesions showed mild to moderate contrast enhancement when compared with precontrast images. There was no statistically significant differences between male and female patients in terms of age, tumor side, involved digit, and highest tumor size. But, tumor volume was slightly larger in female patients compared with male patients (p= 0.083). Discussion: MR imaging is very valuable in the diagnosis of GCTTS because of characteristic internal signal intensity. Also, axial and sagittal images are useful for evaluating the degree of extension around the phalanx, and invasion into the joint and tenosynovial space prior to surgery. These factors can influence the surgical approach.