Chordomas and chondrosarcomas are rare tumors in children, even more so than in adults. Pediatric chordomas predominantly occur in the head and neck. In children, chondrosarcomas occur more frequently in the craniofacial region and in more unusual sites than they do in adults. Tumors of younger children (less than 5 years of age) are more likely to behave aggressively. Management consists of surgery as the primary treatment and postoperative focused radiation of residual disease or tumor margin. In children, as in adults, chemotherapy currently has unclear benefits.
KeywordsChondrosarcoma, Chordoma, Endonasal, Pediatric, Skull base
Cranial base chondroid tumors are rare in the pediatric population. Chordomas constitute only 3% of all primary bone tumors, of which fewer than 5% (reported range: 2%–15%) occur in children (<21 years age). In adults, chordomas occur predominantly in males, with a male to female ratio of about 2:1, but in the pediatric population they may have equal frequency between male and female patients ; however, our series would suggest that the male predilection seen in adults is preserved. Another unique feature of pediatric chordomas is their predilection for the skull base. In adults, most chordomas arise in the sacrococcygeal area and about a third arise at the skull base. In contrast, nearly 75% of pediatric tumors involve the skull base followed by the mobile spine and then the sacrococcygeal area. The clivus is the most common location; almost all tumors in patients younger than 5 years occur there. Older children can have tumors in the maxilla, orbit, nasopharynx, and axial spine. Rare locations such as the gluteal muscle and mediastinum have also been reported. The mean age of diagnosis in the pediatric population is about 10 years.
Even though chondrosarcoma is the third most common primary bone tumor (15%–22%), it is rare in children. About 4% of all cases occur in patients younger than 21 years. Chondrosarcomas can be primary or secondary, arising from benign cartilaginous lesions. As in adults, there is a male predominance. Irradiation of chondrosarcomas, particularly in children, carries significant risk for the development of bone sarcomas (commonly osteosarcoma and fibrosarcoma). Chondrosarcomas account for 9% of all cases of radiation-induced bone sarcomas in children. Although, as in adults, pediatric chondrosarcomas present more commonly in the pelvis, extremities, and the thoracic cage, there is a four times higher frequency of craniofacial tumors in children. Huvos reported a 13% frequency of craniofacial tumors in 79 pediatric chondrosarcomas, compared with the 3.5% frequency reported in adults.
In a review of 79 cases of cranial chordomas in children by Al-Mefty, patients younger than 5 years often presented with symptoms of elevated intracranial pressure and long tract signs. This may reflect the higher incidence of clival lesions in this age group. With this exception, children with chordomas and chondrosarcomas present with signs and symptoms similar to those of adults. Older patients (5–20 years) with cranial lesions often present with headache and double vision (abducens nerve palsy). Depending on the location of the tumor, they can also present with hypoglossal nerve palsy, nasal obstruction, dysphagia, and ataxia. Patients may also present with a retropharyngeal mass with associated breathing and swallowing problems ( Fig. 36.1 ).
The preoperative evaluation is important to fully document the patient’s deficits. Physical examination should include a complete assessment of cranial nerve function. In patients with nasal congestion or airway obstruction, evaluation by otolaryngology should be performed and include nasal endoscopy. Symptoms of hearing loss or vestibular dysfunction can be evaluated further with audiometric testing and vestibular tests if necessary. Lower cranial nerve dysfunction may require evaluation of swallowing function and aspiration risk with a functional endoscopic examination of swallowing or radiography (barium esophagram).
Patients with sacrococcygeal chordomas most often present with pain, constipation, and less often, neurologic symptoms related to the involvement of the cauda equine. About 90% will have a palpable presacral mass on rectal examination. Pain and a palpable mass are also presenting features of pelvic chondrosarcomas.
Magnetic resonance imaging is the preferred test for both initial diagnosis and follow-up. The radiographic characteristics in children are similar to adults. Children can have tumors in unusual locations. For lesions involving the skull base and extending into the upper cervical spine, it is useful to image the entire tumor, which may require extending standard brain protocols into the cervical spine or extending the standard spine protocol into the skull base. Since most patients will receive multimodality treatment that may span multiple institutions, it is helpful to use similar imaging techniques to improve comparison across studies. A computed tomographic scan provides excellent definition of the bony anatomy at the skull base tumor, which is useful in planning the surgical approach ( Fig. 36.2 ).
Young children (younger than 5 years) may harbor poorly differentiated tumors. These may have different imaging characteristics because of their hypercellularity, often more hypodense on T2 with significant postgadolinium enhancement. The Chordoma Foundation recommends total spine imaging at some point around diagnosis, as some patients will harbor benign notochordal rests or tumors, chondromas, or even other coincident chordomas. Finally, epidural venous metastasis may occur in a delayed fashion, typically in the cervical spine, as a mode of regional spread from the skull base.
The histology of pediatric tumors is similar to that of adult lesions, with a few exceptions. Three histological subtypes are described: classical, chondroid, and dedifferentiated. The classical subtype consists of physaliferous tumor cells with vacuolated cytoplasm giving it a “bubbly” appearance, and the chondroid type has features of chordoma and chondrosarcoma. Almost two-thirds of cranial chordomas in children younger than 5 years have the dedifferentiated histological pattern. This variant has a more sarcomatous appearance with cells arranged in sheets, clusters, or nodules. Necrosis is common. Tumors from older children, in contrast, more often (∼80%) have a classic pattern. Overall, 65% of pediatric tumors have a classic pattern; 22% are dedifferentiated, and 13% are chondroid. Histological grading of pediatric chondrosarcomas is similar to that for tumors in adults. Mesenchymal chondrosarcomas occur more frequently in adolescents (25% in one series).
For both chordomas and chondrosarcomas, surgery is the initial treatment. Radical excision of tumor with tumor-free margins is the goal. The locally aggressive biology of the tumor makes complete resection a challenge, especially given the close proximity to critical neurovascular structures, including the internal carotid artery (ICA). Large tumors may require staged surgeries using multiple approaches ( Fig. 36.3 ). With improvements in instrumentation and training of skull base teams, the endoscopic endonasal approach to pediatric skull base lesions has become a reality. Although the principles of surgery are the same for adult and pediatric patients, pediatric patients present unique challenges, both anatomic and physiologic. Staging is common, reconstruction even more challenging, and it is important to have a skull base team with adequate expertise and experience. This may include both adult and pediatric otolaryngologists and neurosurgeons. This can result in gross total or near-total resections in most pediatric patients. Tumors that extend into the upper cervical spine may also require occipital cervical stabilization. Image guidance helps identify anatomical structures. Neurophysiologic monitoring is a critical adjunct to surgery. Monitoring of cortical function (somatosensory evoked potentials) provides an overall assessment of cerebral perfusion and can be adversely affected by hypotension or subdural collections of air or fluid. Brainstem evoked responses used to monitor brainstem function for surgeries of the posterior fossa, and electromyography is used to monitor motor function of cranial nerves.