A case of neuroblastoma arising from the posterior mediastinum directly invading a rib

Abstract

A 3-year-old boy with no medical history presented with fever and dyspnea to his previous physician. Computed tomography demonstrated a posterior mediastinal tumor, an osteolytic lesion on the left 8^th rib, and marked pleural thickening and pleural effusion in the left thoracic cavity. These imaging findings strongly suggested a primary bone neoplasm. A soft tissue neoplasm such as Askin tumor was suspected, and chemotherapy was begun. However, the pathological report of the tumor biopsy revealed poorly differentiated neuroblastoma. No distant metastasis was apparent. The mitosis-karyorrhexis index was low, and no MYCN amplification was detected. The tumor was assessed to be at stage 3 on the basis of the International Neuroblastoma Staging System, and the patient was considered to be at high risk. After chemotherapy following the JNBSG protocol, he underwent surgical resection of the mediastinal tumor. The tumor beds were subjected to proton beam therapy, followed by high-dose chemotherapy with autologous peripheral blood stem cell transplantation. The patient was further treated with retinoic acid, and has presented no sign of recurrence 2 years after the completion of therapy.