Chordoma

Tumor biology and incidence

Low-grade malignant tumor
Generally located at base of skull (clivus), sacrum, or spine (less common)
Thought to arise from primitive notochordal remnants in the axial skeleton
Present in a central, axial-based location, most often anteriorly
Cumulative case count published in The Burden of Musculoskeletal Disease (AAOS) identified 2,339 chordomas over a period of 20 years, or annual incidence of 117 chordomas in the US within the studied population
- Other estimates as high as 300 cases per year

Age

Most occur in older patients, especially those older than age 40
Rarely occur before age 30

Gender

M:F = 2:1

Presentation

Symptoms generally of long duration due to slow growth of lesion and delay in diagnosis
Symptoms usually nonspecific, depending on location of tumor
- Cervical spine: Hoarseness, dysphagia, bleeding
- Sacrum: Vague low back pain, constipation, lower extremity radiculopathy, palpable mass
  - Bowel and bladder dysfunction resulting from local organ mass effect or autonomic dysfunction
    - Autonomic dysfunction can result as the tumor compresses the adjacent sympathetic or parasympathetic outflow
Obtain history of treatment for degenerative disc disease or coccydynia
Obtain history of bowel, bladder, and sexual function

Physical findings

Abnormal rectal tone, perineal sensation possible
Soft tissue mass may be palpable on rectal exam

Plain films

Lesion may be missed on plain films; changes generally subtle
Findings may be masked by overlying abdomina/bowel gas on AP of pelvis

Site

Sacrococcygeal lesions
Spheno-occipital lesions
Vertebral body lesions (in descending order of occurrence): cervical, thoracic, lumbar

Size

Slow growing lesion; can be quite large by time of diagnosis

Tumor effect on bone

Local lytic destruction of bone; extension into surrounding soft tissues

Bone response to tumor

Sclerotic, irregularly scalloped bony margin

Matrix

Calcified secondary to calcification of necrotic tissue/debris within tumor (rare)

Cortex

Cortical breakthrough (common)

Soft tissue mass

Common; more apparent on MRI than on plain films

CT scan

Useful for assessing degree of osseous involvement, as well as proximity of tumor mass to adjacent pelvic organs
Chest CT for systemic staging

MRI

Need multiple axes to accurately stage extent of lesion and plan surgery
Superior soft tissue resolution with respect to involvement of neurovascular structures within pelvis and spinal canal
Chordomas mucinous; lesions typically appear hypointense on T1-weighted images and hyperintense on T2-weighted images
Characteristic lobular, heterogeneous features
Occasionally, contrast fluid-fluid levels can be identified in cystic portions of mass

Differential diagnosis

Metastasis
Chondrosarcoma
Myeloma
Lymphoma
Giant cell tumor

Natural history

Will continue to grow; symptoms related to location
May dedifferentiate into higher-grade lesion with sarcomatous component (rare)
Difficult to resect, leading to frequent local recurrence
- Local recurrence in lumbosacral plexus devastating complication
- Radiation plus local resection may reduce risk of local relapse
Metastases usually very late feature

Pathology

Gross: Lobulated, myxoid tissue
Microscopic: Tumor cells are in sheets or cords in an abundant myxoid stroma
Cells often vacuolated, displacing the nucleus eccentrically
Physaliferous cells may be present
Cytological atypia may be present; no clinical significance
High mucin content within cytoplasm and in matrix renders a deep, eosinophilic appearance on H&E stained sections.
Chondroid appearance, particularly in clival-based tumors; may indicate a better prognosis
Dedifferentiated form of chordoma has poor prognosis.
Characterized immunohistochemically by S100 and epithelial membrane antigen positivity

Diagnosis and treatment

Biopsy, in consultation with musculoskeletal surgical oncolgist
- Avoid transrectal biopsy; would necessitate rectal resection and colostomy
- Avoid tumor spillage by using posterior needle biopsy
Maintain of treatment: surgical resection with clear margins; chemotherapy ineffective
- Wide resection can be curative; however 50% recurrence rate has been reported, which reduces chance of cure for patient
- Resection of upper sacral lesions (S2 or above) carry an increased risk of blood loss, major complications, and longer ICU stays
Radiation therapy possibly useful in cases with microscopically positive margins of resection, palliative treatment of unresectable lesion
Median survival is 6 years
- Overall survival rates: 70% at 5 years, 40% at 10 years
- After development of metastases, median survival diminishes greatly