2022 Volume 59 Issue 2 Pages 192-196
A three-year-old boy presented with abdominal pain. Computed tomography (CT) revealed a left renal tumor and bilateral lung metastases. Tumor biopsy revealed clear cell sarcoma of the kidney. Bone scans showed no abnormal radiotracer accumulation. The patient received preoperative chemotherapy according to the Japan Wilms Study Group protocol regimen. CT showed shrinkage of the primary lesion and lung metastases after the chemotherapy. Subsequently, a left nephrectomy was performed. Postoperatively, chemotherapy was continued in combination with radiotherapy, reducing the size and number of lung metastases. However, CT showed new osteosclerotic lesions in the vertebral body, ilium, and femur. Moreover, bone scans revealed abnormal radiotracer accumulation in the vertebral body. We initially suspected bone metastases; however, lung metastasis shrinkage suggested a flare phenomenon—an increased radiotracer accumulation despite a good response to the treatment. Therefore, the same chemotherapy was continued. A follow-up bone scan revealed a decreased intensity of vertebral body The flare phenomenon should be considered when there is an inconsistency between clinical and bone scan findings.
