The treatment of an unusual case with severe kyphoscoliotic deformity of the thoracolumbar spine, in association with a ganglioneuroblastoma invading the adjacent diaphragm, is presented in this report. Severe scoliotic deformity of the spine, associated with ganglioneuroblastoma of the diaphragm is a rare combination and treatment can be very challenging, as both entities require extensive surgery. To the best of our knowledge, only two reports related to a similar condition have been published in the literature so far. A 9-year-old girl had been treated in another institution since the age of 5 years for thoracolumbar kyphoscoliosis with bracing. She was referred to our department with a stiff right kyphoscoliotic curve at the thoracolumbar region (T8-L2), with measurements of 105 and 90° for the scoliotic and kyphotic elements, respectively. There were no neurological signs detected at the preoperative work-up, which included clinical and radiological evaluation (plain X-rays and computed tomographic scan). The patient was treated with a two-stage spinal fusion. During the anterior approach through a right thoracotomy, a tumor was discovered infiltrating half of the diaphragm and extended to the frontal surface of the lower thoracic vertebral bodies. The vertebrae were cleared of the tumorous masses and anterior discectomies (T8-L2) were successfully carried out according to the preoperative plan. The histopathology report indicated ganglioneuroblastoma in both the prevertebral material and the speciments excised from the diaphragm. A week later a T3-L4 posterior fusion was carried out and the deformity was corrected and fixed with an SFS instrumentation system. Both the scoliotic and the kyphotic curves were reduced to 46°. Postoperatively the patient was referred to the oncology department of another hospital for the treatment of the diaphragm tumor. During the last follow-up (4 years), the scoliotic curve remains steady and the tumor shows no recurrence. Although there are cases of ganglioneuroblastoma associated with scoliotic deformity, the combination of this tumor infiltrating the diaphragm and a very severe deformity of the spine is extremely rare. Nevertheless, the treatment undertaken has proven to be successful so far.