Notochordal Tumours
• Notochordal tumors may be benign or malignant
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Notochordal Tumours V. N. Cassar-Pullicino and D. C. Mangham
Contents
K ey P oi n t s 20.1
Introduction 375
20.2 Notochordal Remnants 376 20.3
Benign Notochordal Cell Tumours 376 20.3.1 Clinico-Pathological Considerations 376 20.3.2 Imaging Considerations 379 20.4
Incipient Chordoma 380
20.5 Classic Chordoma 381 20.5.1 Clinico-Pathological Considerations 381 20.5.2 Imaging Considerations 382 20.5.3 Prognosis 387 20.6
Chondroid Variant of Classic Chordoma 388
20.7
Dedifferentiated Chordoma 389
20.8 Extra-Axial Chordoma 389 20.9
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Notochordal tumors may be benign or malignant Notochordal tumors have a predilection for the spheno-occipital and sacral regions Benign notochordal tumors tend to be detected on MRI but demonstrate little or no abnormality on radiographs, CT or bone scintigraphy. Chordoma accounts for 50% of malignant sacral tumors. Sacral chordomas are predominently osteolytic with 90% showing varying degrees of calcification on CT, all showing an anterior soft tissue mass and 77% a posterior soft tissue mass on MRI. Biopsy identification of choirdoid tissue needs to be carefully correlated with MRI and CT appearances to decide if it represents BNCT or chordoma.
Conclusion 389 References 390
20.1
Introduction
Victor N. Cassar-Pullicino, MD Consultant Radiologist Department of Radiology The Robert Jones & Agnes Hunt Orthopaedic and District Hospital NHS Trust Gobowen, Oswestry, Shropshire SY10 7AG, UK D. C. Mangham Consultant Pathologist Department of Musculoskeletal Pathology The Robert Jones & Agnes Hunt Orthopaedic and District Hospital NHS Trust Gobowen, Oswestry, Shropshire SY10 7AG, UK
The notochord is a posterior midline axial structure which plays a vital, albeit transient, role in human embryology, acting as the major structural organiser of spinal development. Before the second month it is surrounded by sclerotomes forming the ossification centres of the vertebral column lying anterior to the neural tube. As the embryonic spine develops, the notochord acts as an inducer of chondrification and segmentation of the mesenchymal elements. It involutes and fragments as development progresses, and by the second embryological month it persists in the intervertebral residues which later form the nucleus pulposus of the foetal and infant intervertebral disks up to three years of age (Salisbury 1993; Pazzaglia et al. 1989). Histologically the morphologically characteristic cell of noto-
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V. N. Cassar-Pullicino and D. C. Mangham
chordal tissue is termed the physaliferous cell in which multiple cytoplasmic vacuoles indent the central nucleus, while immunohistochemically notochordal cells express the antigenic phenotype of cartilage and epithelial cells being strongly positive for S-100 protein, cytokeratin and epithelial membrane antigen (EMA). This morphology and immunophenotype of notochordal tissue is retained and manifested by notochordal tumours (Crapanzano et al. 2001). Tumours of the notochord are unusual for a variety of reasons. Notocho
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