Giant Cell Tumor of Tendon Sheath Affected Guyon Canal: A Case of Ulnar Tunnel Syndrome

Despite its low prevalence, giant cell tumor of tendon sheath (GCTTS) is considered as one of the most common benign tumors in the hand. GCTTS mostly affects tendon sheaths and finger joints; however, its presence in the wrist and Guyon canal is scarcely reported.
In this report, we describe the case of a 32-year-old female with signs and symptoms of ulnar tunnel syndrome in her right hand while the MRI illustrated a soft tissue mass in the Guyon canal. Excisional biopsy was performed, confirming the diagnosis of GCTTS.
This report proposes the consideration of GCTTS as a differential diagnosis in patients suffering from ulnar tunnel syndrome. In addition, it could be concluded that an excisional biopsy might be considered as a therapeutic and diagnostic method in this disease.