Extraarticular paravertebral diffuse-type giant cell tumor

Pediatric giant cell tumor of the tendon sheath of the craniocervical junction involving the occipital condyle

INTRODUCTION

Giant cell tumor of the tendon sheath (GCTTS), also called pigmented villonodular synovitis, is a common lesion of the synovial membrane of the hand joint, but it uncommonly involves the axial skeleton, especially in pediatric populations. Furthermore, GCTTS originating from the occipital condyle has not been reported previously.

CASE REPORT

A 15-year-old girl presented with a palpable neck mass for 1 year, and imaging studies revealed a less demarcated and heterogeneously enhanced mass in the suboccipital region. The tumor was originating from the occipital condyle that eroded the skull and atlas, and it was completely resected via a far lateral transcondylar approach followed by transarticular screw fixation. After the resection, we performed occipitocervical fusion to prevent spinal instability. The patient made an uneventful recovery after surgery. Recurrence has not been observed after 5 years of follow-up.

DISCUSSION

We report this rare case and briefly review the general features and unusual locations of GCTTS with recommendations for treatment modalities.

Pigmented villonodular synovitis: radiologic-pathologic correlation

Pigmented villonodular synovitis (PVNS) represents an uncommon benign neoplastic process that may involve the synovium of the joint diffusely or focally (PVNS) or that may occur extraarticularly in a bursa (pigmented villonodular bursitis [PVNB]) or tendon sheath (pigmented villonodular tenosynovitis [PVNTS]). Pathologic specimens of the hypertrophic synovium may appear villous, nodular, or villonodular, and hemosiderin deposition, often prominent, is seen in most cases. The knee, followed by the hip, is the most common location for PVNS or PVNB, whereas PVNTS occurs most often in the hand and foot. PVNTS is also referred to as giant cell tumor of the tendon sheath (GCTTS). PVNTS is the most common form of this disease by a ratio of approximately 3:1. Radiographs reveal nonspecific features of a joint effusion in PVNS, a focal soft-tissue mass in PVNB or PVNTS, or a normal appearance. Extrinsic erosion of bone (on both sides of the joint) may also be seen and is most frequent with intraarticular involvement of the hip (>90% of cases). Cross-sectional imaging reveals diffuse involvement of the synovium (PVNS), an intimate relationship to the tendon (PVTNS), or a typical bursal location (PVNB), findings that suggest the diagnosis. However, the magnetic resonance (MR) imaging findings of prominent low signal intensity (seen with T2-weighting) and "blooming" artifact from the hemosiderin (seen with gradient-echo sequences) are nearly pathognomonic of this diagnosis. In addition, MR imaging is optimal for evaluating lesion extent. This information is crucial to guide treatment and to achieve complete surgical resection. Recurrence is more common with diffuse intraarticular disease and is difficult to distinguish, both pathologically and radiologically, from the rare complication of malignant PVNS. Recognizing the appearances of the various types of PVNS, which reflect their pathologic characteristics, improves radiologic assessment and is important for optimal patient management.