UNASSIGNED: Giant cell tumor of the tendon sheath (GCTTS) is commonly seen in the appendicular skeleton, and rarely arises from the axial skeleton. We describe a rare case of GCTTS in an adolescent in the upper cervical spine.
UNASSIGNED: A previously healthy 16-year-old boy presented with a 6-month history of numbness of right upper extremity, and had experienced a neck pain 4 months ago. Spinal MRI demonstrated a small syrinx at C2 level and a well-circumscribed extradural mass with contrast enhancement extending from the posterior arch of C1 to C2. The extradural mass was totally resected, and the syrinx underwent clinical and imaging surveillance.
UNASSIGNED: GCTTS should be considered in the differential diagnosis of the axial skeletal lesion although very rare. Gross-total resection is advocated in GCTTS of the upper cervical spine, and subtotal resection with meticulous lesion monitoring should be performed in unresectable cases.

Tenosynovial giant cell tumor (TSGCT) represents a family of benign tumors that arise from the synovial tissue of a joint, tendon sheath, or bursa. It usually involves the joints of the extremities and rarely occurs in the head and neck region. Here, we describe a case of a 32-year-old man with a submucosal mass bulging in the posterior pharyngeal wall since one month. The lesion was removed and diagnosed with localized type of TSGCT based on histopathological investigations and clinical presentation. It is very rare that TSGCT occurs in the retropharynx, which reminds clinicians to consider this entity as a possible diagnosis.

The present study aimed to investigate the value of magnetic resonance imaging (MRI) in the diagnosis of giant cell tumor of the tendon sheath (GCTTS), including localized (L-) and diffuse (D-) types. A total of 38 patients with GCTTS, including 31 with L-GCTTS and 7 with D-GCTTS, diagnosed by surgery and pathology, were retrospectively analyzed. All patients underwent MRI examination. Of the 31 patients with L-GCTTS, the tumors were located in the hand and wrist (18 patients), the ankle and foot (10 cases), the knee joint (2 cases) and the temporomandibular joint (1 case). All 31 lesions were either located in relation to a tendon or were partially/completely enveloping it and all were well marginated. With respect to the 7 D-GCTTS patients, the tumors were located in the ankle and foot (6 cases) or the hand and wrist (1 cases). All 7 lesions presented as an aggressive soft tissue mass infiltrating the tendon sheath and adipose tissue around the joint. The characteristic internal signal of GCTTS, including L-GCTTS and D-GCTTS, was demonstrated by MRI examination. MRI is currently the optimal modality for preoperative assessment of tumor size, extent and invasion of adjacent joint and tenosynovial space.

Giant cell tumor of the tendon sheath (GCTTS) predominantly occurs in the tendon sheaths of the hand, but rarely in those of the knee. The current study reports the case of a 36-year-old male patient presenting with anterior knee pain. The patient was ultimately diagnosed with GCTTS in the knee mimicking patellar tendinopathy. To the best of our knowledge, this is the first case of its kind. Magnetic resonance imaging revealed a well-defined oval intra-articular lesion located at the proximal segment of the infrapatellar fat pad. The lesion was completely excised under arthroscopy and pathological examination confirmed the diagnosis of GCTTS. There was no evidence of recurrence at the 2-year follow-up examination. The findings of the present study suggest that, despite its rarity, GCTTS should be considered in the differential diagnosis of patellar tendinopathy.

The current study presents the case of a 25-year-old male who developed tumor recurrence of the proximal phalange of the ring finger on the right hand 4 years after partial tumor resection surgery. An X-ray of the right hand showed that the distal bone of the proximal phalange on the ring finger was destroyed. An artificial finger joint replacement was performed using a silicone joint for this unusual tumor recurrence. The pathological findings were indicative of a giant cell tumor of the tendon sheath. As a result of surgery, the patient\'s proximal interphalangeal point motion recovered to the pre-operative level. The pre-operative and post-operative disabilities of the arm, at shoulder and hand and total activity measurement values were 1.67 and 3.33, and 255 and 243°, respectively. Complications such as tumor recurrence, joint dislocation and the requirement for prosthetic training were not observed during the 5-year follow-up period.