ARRS 2022 Abstracts

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E1231. Multimodality Imaging Features of Tenosynovial Giant Cell Tumors with Emphasis on PET/CT
Authors
  1. Kenneth Huynh; University of California, Irvine
  2. Ba Nguyen; Mayo Clinic Scottsdale
Background
Tenosynovial giant cell tumors (TSGCT) refer to a collection of rare, benign tumors involving the synovium, bursae, and tendon sheaths. These tumors are further classified into two subtypes: localized TSGCT (nodular tenosynovitis and giant cell tumor of tendon sheath) and diffuse TSGCT (diffuse-type giant cell tumor and pigmented villonodular synovitis). TSGCTs have been associated with a clonal neoplastic process, harboring a chromosomal translocation, t(1;2)(p13;q37), leading to overexpression of CSF-1 and subsequent secondary inflammatory changes. Progression of disease may lead to chronic, debilitating joint degeneration and impairment. Prompt and accurate diagnosis of TSGCTs is crucial as surgical and medical intervention of these tumors can substantially improve quality of life; however, radiologists should be wary as imaging features of TSGCTs may mimic malignant processes.

Educational Goals / Teaching Points
The goals of this exhibit are to 1) present the different subtypes of TCGCTs and discuss their epidemiology, pathogenesis, clinical manifestations, and differential diagnosis; and 2) characterize the multimodality imaging features of TSGCTs, with emphasis on PET/CT in diagnosis, recurrency, and post-therapeutic surveillance.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
TSGCTs are typically well-circumscribed, encapsulated tumors that may be found in intra-articular or peri-articular locations. On radiographs, degeneration of the surrounding bone and cartilage can be seen. MRI will show T1- and T2-weighted hypointensity. TSGCTs will demonstrate contrast enhancement, and signal voids representing hemosiderin deposition (“blooming artifact”) may be seen. Ultrasonography will show homogeneous, hypoechoic masses with detectable internal vascularity. Although these tumors are benign, overexpression of CSF-1 and secondary inflammatory changes result in FDG-avidity and may mimic malignant processes on PET/CT. Treatment includes surgical resection, radiation therapy, and medical therapy with tyrosine kinase inhibitors and CSF-1 receptor inhibitors. The role of PET/CT is highlighted in evaluating response to treatment and detecting tumor recurrence.

Conclusion
This educational exhibit will familiarize radiologists with the characteristic imaging features of TSGCTs through multiple modalities and describe the utility of PET/CT in the management of these tumors.