Metastasis of Renal Cell Carcinoma

Clinical History

Complaints of prostatism and pain in the right hip. History of renal carcinoma which was treated by nephrectomy 8 years ago and Paget’s disease of the right hemipelvis and proximal right femur known for 20 years.

Imaging Findings

The patient complained of prostatism and pain in the right hip. His medical history revealed a renal carcinoma which was treated by nephrectomy 8 years before and Paget’s disease of the right hemipelvis and proximal right femur known for 20 years. Plain radiograph and CT scan were performed and showed Paget’s changes at the pelvis and an osteolytic lesion proximal in the right femur. Subsequently MRI and needle biopsy under CT guidance were carried out. Histology after CT guided biopsy of the right trochanteric region showed a metastasis of renal cell carcinoma.

Discussion

Neoplastic involvement in Paget’s disease is possible and includes sarcomatous transformation, giant cell tumor transformation, superimposed metastatic disease (breast, lung, kidney, prostate and colon), plasma cell myeloma or lymphoma. There are no studies reporting the incidence of metastases compared to sarcomatous degeneration. Moreover, there are conflicting reports whether metastases occur more or less frequently than metastases in normal bone. Increased local blood flow in Paget’s disease could be responsible for increased metastatic disease. Both sarcomatous degeneration and metastatic lesions may be responsible for increased local pain and soft tissue swelling. Radiologically osteolytic lesions within a pagetic bone and/or a soft tissue mass can be found. The lytic lesions are best demonstrated on conventional radiographs and CT, whereas soft tissue extension is best visualized on MRI. Needle biopsy with histological study of the specimen is mandatory to confirm the presumed diagnosis.

Differential Diagnosis List

Final Diagnosis

Metastasis of renal cell carcinoma

URL:	https://eurorad.org/case/925
DOI:	10.1594/EURORAD/CASE.925
ISSN:	1563-4086