Long bone metastases of renal cell carcinoma imaging features: case report and literature review

Abstract

Abstract Objectives This article analyzed the imaging features of 18 long bone metastasis (LBM) of renal cell carcinoma (RCC) confirmed by pathology and reviewed the available literature. Case presentation Patients who underwent radiographic examinations at our hospital between January 2015 and December 2021 with pathology-confirmed bone metastases were evaluated. The clinical and radiographs and CT, and MR images features of the patients were analyzed. Eighteen patients with pathology-confirmed LBM from RCC were collected. All the patients had X-ray examinations, 15 had computed tomography (CT), 13 had magnetic resonance (MR) imaging, and six had MR enhancement. The clinical and imaging features of the lesions were analyzed, including morphological and signal intensity characteristics. Ten patients were found with metastases after nephrectomy, and eight patients were admitted to the hospital with skeletal-related events (SREs). Eighteen cases originated from clear cell RCC. Fourteen lesions were located in the epiphysis and four in the diaphysis. The height-to-width ratio of the lesions ranged from 1.11 to 3.41 (mean, 1.84). All lesions showed osteolytic destruction, with 16 lesions showing expansile destruction. Seven lesions demonstrated soap bubble hyperintensity and hypointense separation on T2-weighted images. Six lesions demonstrated a flow-void sign, and six showed marked marginal enhancement. Conclusions The LBM of RCC mainly occurred in the proximal epiphysis and tended to spread along the long bone axis with expansile osteolytic destruction. In some cases, soap bubble hyperintensity, hypointense separation, and the flow-void sign were seen.