Tenosynovial Giant Cell Tumor of Diffuse Type Mimicking Bony Metastasis Detected on F-18 FDG PET/CT

FDG PET/CT in Tenosynovial Giant Cell Tumor of the Lumbar Facet Joint

ABSTRACT

Tenosynovial giant cell tumor rarely affects the facet joints of the spine. We describe FDG PET/CT findings in a case of tenosynovial giant cell tumor arising from the left L2 to L3 facet joint. The tumor caused osteolytic bone destruction of the facet joint and showed intense FDG uptake with SUVmax of 10.4. This case indicates tenosynovial giant cell tumor should be included in the differential diagnosis of abnormal facet joint FDG accumulation.

Diffuse-Type Tenosynovial Giant Cell Tumor of the Thoracic Spine: Appearance on FDG PET/CT

D-TGCT (diffuse-type tenosynovial giant cell tumor) is a benign proliferative disorder of the synovial membranes that usually occurs in the appendicular skeleton, especially large joints such as the knee, hip, and elbow. It rarely involves the spine. In this report, we describe a rare case of D-TGCT in the thoracic spine, which showed a lytic lesion with high FDG uptake. It can mimic metastases or neurogenic tumors and should be included in the differential diagnosis of spinal tumors.

Diffuse-Type Tenosynovial Giant Cell Tumor of the Shoulder Evaluated by FDG PET/CT

Diffuse-type tenosynovial giant cell tumor is a locally aggressive neoplasm that typically involves the knee and hip but rarely involves the shoulder. In this case, a 74-year-old woman presented a painless mass in the right shoulder. FDG PET/CT demonstrated intense FDG uptake with an SUVmax of 19.2 in the lesion. The mass was dissected and confirmed as diffuse-type tenosynovial giant cell tumor by pathology. Follow-up FDG PET/CT assessment revealed more extensive soft tissue infiltration and adjacent bone erosion 3 years after surgery. Thus, FDG PET/CT well demonstrated the hypermetabolic and local aggressive characteristics of the lesion.

Successful treatment of a diffuse type tenosynovial giant cell tumor in the thoracic spine mimicking spinal metastasis by frozen recapping laminoplasty in a patient with thyroid cancer

PURPOSE

Tenosynovial giant cell tumor of the diffuse type (TGCT-D) involving the spine is rare. Its differential diagnosis includes metastatic disease; however, there have been few reports of spinal TGCT-D mimicking spinal metastasis in patients with a history of malignancy.

METHODS

We report on a 35-year-old woman with a history of papillary thyroid cancer who was diagnosed with TGCT-D of the thoracic spine mimicking spinal metastasis. Preoperative computed tomography (CT) revealed a 1.0 × 1.0-cm lytic bone lesion involving the left T7 vertebral lamina, pedicle, and the T6-7 facet joint; the thoracic spine lesion was markedly fluorodeoxyglucose-avid on positron-emission tomography/computed tomography (PET/CT).

RESULTS

Spinal metastasis was initially suspected given the patient's history of papillary thyroid cancer. Total excision was performed with recapping laminoplasty. The resected lamina was frozen in liquid nitrogen and used as a frozen autograft (frozen recapping laminoplasty) for spinal reconstruction with posterior instrumentation. Histological findings supported a diagnosis of TGCT-D. The patient had no evidence of local recurrence 2 years post-surgery. Bone union was achieved 3 years post-surgery.

CONCLUSIONS

TGCT-D can mimic metastasis in PET/CT and should be included in the differential diagnosis if a lytic lesion affecting the posterior elements of the vertebrae involves the facet joints. CT-guided biopsy is recommended for accurate diagnosis when an occult tumor, such as TGCT, is incidentally detected on PET-CT, even in patients with a history of malignant neoplasm. Frozen recapping laminoplasty is useful for complete resection of a spinal tumor, preventing local recurrence, and preservation of the posterior spinal elements.