Summary
Description
Chordoma is a malignant tumor that usually occurs in the sacrum, coccyx, or at the base of the skull. It arises from notocord remnants.
People and Age
Chordoma usually occurs within the fifth to seventh decade.
Symptoms and Presentation
Chordoma in the sacrum and coccyx may present as "low low" back pain or tenderness, or with symptoms of obstruction such as constipation or painful bowel movements.
Brief description of the xray
On plain X-ray, chordomas appear as a solitary mid-line lesion with bony destruction. There is often an accompanying soft tissue mass.
Complete Information on this Tumor
Introduction and Definition
Chordoma is a rare malignant tumor that arises from notochord remnants. Chordomas account for 1 to 4% of all bone tumors. They occur in older adults with the highest prevalence in the fifth to seventh decade. Due to their origin in the notochord, chordomas occur in the mid-line of the axial skeleton. One half of cases occur in the sacrococcygeal region and one third occur at the base of the skull. Other more uncommon sites include transverse processes of vertebrae and the paranasal sinuses.
Incidence and Demographics
Chordoma has an incidence ratio for male v. female of two to one.
Symptoms and Presentation
The clinical presentation depends on the location of the tumor. Sacrococcygeal tumors often present as low back pain with no characteristic pattern or time course. Sacrococcygeal tumors can also present as bowel and bladder dysfunction. Presacral tumors can often be palpated on rectal exam, but this simple examination technique is often overlooked. Sacral tumors are often large at presentation as a large volume of tumor can be accommodated within the pelvis. Anterior cervical tumors can present as dysphagia and posterior cervical tumors can cause neurological deficits. Tumors at the base of the skull may present with headaches.
X-Ray Appearance and Advanced Imaging Findings
On plain x-ray, chordomas appear as a solitary mid-line lesion with bony destruction. The bone surrounding the tumor is gradually and completely destroyed. The sacrum may appear enlarged due to the tumor. There is often an accompanying soft tissue mass. Associated findings due to the pelvic mass may include displacement of the bladder, uterus, or rectum. Approximately half of the time focal calcifications are present. Remnants of the original bone may persist in the tumor. CT and MRI scans help demonstrate the soft tissue component, calcifications and epidural extension. MRI is helpful in identifying local recurrences. Chordomas have reduced uptake on bone scan.
Differential Diagnosis
Other tumors in these locations include metastatic adenocarcinoma from breast, lung, kidney, thyroid, prostate and GI sources.
Preferred Biopsy Technique for this Tumor
Transrectal biopsy should be avoided due to the resulting contamination of the GI tract , which makes surgical cure less likely.
Histopathology findings
The cut surface of the tumor is lobular, greyish, mucoid, and semi-transparent. Focal necrosis is common. Microscopically, chordomas are characterized by lobules and fibrous septa. The malignant cell has eosinophilic cytoplasm. Prominent vacuoles of mucus push the nuclei to the side resulting in "physaliphorous" cells from the Greek word for bubble or drop. Mitotic figures are relatively infrequent.
Treatment Options for this Tumor
Due to the location of chordomas, treatment is difficult. Wide surgical excision is the treatment of choice but can be difficult or impossible to achieve due to the anatomic extent of the tumor. Positive margins are common, and ultimately lead to local recurrence. Recurrence is reported approximately 50% of cases of sacral and coccygeal chordoma. Recurrence is usually followed by additional, partially successful surgery, and the tumor becomes progressively more difficult to treat surgically. Adjuvant treatments such as radiation and proton beam therapy, as well as others, have been extensively used for difficult, recurrent, or unresectable cases with considerable success. The tumor is relatively resistant to radiation, and the the morbidity of radiation can be particularly severe due to the location of the tumor. Chemotherapy can be used for late stage disease.
Preferred Margin for this Tumor
A wide excision is preferred.
Outcomes of Treatment and Prognosis
Treatment is limited due to the location of the tumor. With sacrococcygeal tumors, sexual function and sphincter control may be compromised after surgery. Chordomas metastasize to lymph nodes, lungs, liver and bone. Metastasis is reported in 25-30% of cases. The 10 and 20 year survival is 64% and 52%, according to reports.
Special and Unusual Features
During the fourth to sixth week of fetal development mesenchymal cells from individual sclerotomes merge to surround the notochord and form the vertebral bodies. The notochord normally degenerates and remnants form the nucleus pulposus of the vertebral disc. The prevailing theory is that in chordomas the notochord fails to degenerate and then undergoes malignant transformation. The major failing of this theory is that normal notochord remnants have never been observed.
Suggested Reading and Reference
Healey, JH and JM Lane, Chordoma: A Critical Review of Diagnosis and Treatment, Orthopedic Clinics of North America, 20(3):417-425, July, 1989.
Bullough, Peter, Orthopaedic Pathologv (third edition), Times Mirror International Publishers Limited, London, 1997.
Huvos, Andrew, Bone Tumors: Diagnosis. Treatment and Prognosis, W.B. Saunders. Co., 1991.
