Small direct right ventricular cardiac metastasis of osteosarcoma in a 10-year-old boy affirmed by cardiac MRI

BACKGROUND: Metastatic osteosarcoma with direct cardiac involvement is an exceptionally rare finding. Reliable detection of cardiac metastases is known to be crucial for patients therapy and prognosis. CASE SUMMARY: In a 10-year-old boy affected by osteosarcoma of the left femur, a baseline Fluorine-18-fluorodeoxy-glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) was performed to assess the full extent of disease. Whole-body scan detected numerous bone metastases together with a single pulmonary metastasis. Moreover, increased tracer uptake was observed in the intracavitary right cardiac ventricle in the position of a subtle spot of calcification. Because of nondetectability of a cavitary lesion on echocardiography, cardiac magnetic resonance imaging (CMRI) examination was performed to evaluate cardiac (18)F-FDG PET/CT finding. CMRI revealed a small nodule in the right ventricle attached to the trabeculae, highly suspicious of a direct cardiac metastasis. After 4 cycles of chemotherapy, complete regression of tracer uptake of the lesion was observed on a follow-up (18)F-FDG PET/CT scan. CONCLUSION: CMRI is able to detect even small, clinically asymptomatic cardiac metastases in young patients affected by osteosarcoma.