Biochemical studies of the matrix of craniovertebral chordoma and a metastasis

Tumor-biology and current treatment of skull-base chordomas

Chordomas are rare, slow growing tumors of the axial skeleton, which derive from the remnants of the fetal notochord. They can be encountered anywhere along the axial skeleton, most commonly in the sacral area, skull base and less commonly in the spine. Chordomas have a benign histopathology but exhibit malignant clinical behavior with invasive, destructive and metastatic potential. Genetic and molecular pathology studies on oncogenesis of chordomas are very limited and there is little known on mechanisms governing the disease. Chordomas most commonly present with headaches and diplopia and can be readily diagnosed by current neuroradiological methods. There are 3 pathological subtypes of chordomas: classic, chondroid and dedifferentiated chordomas. Differential diagnosis from chondrosarcomas by radiology or pathology may at times be difficult. Skull base chordomas are very challenging to treat. Clinically there are at least two subsets of chordoma patients with distinct behaviors: some with a benign course and another group with an aggressive and rapidly progressive disease. There is no standard treatment for chordomas. Surgical resection and high dose radiation treatment are the mainstays of current treatment. Nevertheless, a significant percentage of skull base chordomas recur despite treatment. The outcome is dictated primarily by the intrinsic biology of the tumor and treatment seems only to have a secondary impact. To date we only have a limited understanding this biology; however better understanding is likely to improve treatment outcome. Hereby we present a review of the current knowledge and experience on the tumor biology, diagnosis and treatment of chordomas.

Matrix gene expression analysis and cellular phenotyping in chordoma reveals focal differentiation pattern of neoplastic cells mimicking nucleus pulposus development

Chordoma is the fourth most common malignant primary neoplasm of the skeleton and almost the only one showing a real epithelial phenotype. Besides classic chordoma, so-called chondroid chordoma was described as a specific entity showing cartilage-like tissue within chordomatoid structures. However, since its first description, strongly conflicting results have been reported about the existence of chondroid chordoma and several studies suggested chondroid chordomas being in fact low-grade conventional chondrosarcomas. In the present study, we used cytoprotein expression profiling and molecular in situ localization techniques of marker gene products indicative of developmental phenotypes of chondrocytes to elucidate origin and biology of chondroid chordoma. We were able to demonstrate the chondrogenic potential of chordomas irrespectively of the appearance of overt cartilage formation by identifying the multifocal expression of type II collagen, the main marker of chondrocytic differentiation. Additionally, the cartilage-typical large aggregating proteoglycan aggrecan was present throughout all chordomas and, thus, a very characteristic gene product and marker of these neoplasms. Biochemical matrix composition and cell differentiation pattern analysis showed a high resemblance of classic chordomas and in chordoid areas of chondroid chordomas to the fetal chorda dorsalis, whereas chondroid areas of chondroid chordomas showed features similar to adult nucleus pulposus. This demonstrates on the cell function level the chondrocytic differentiation potential of neoplastic chordoid cells as a characteristic facet of chordomas, mimicking fetal vertebral development, ie, the transition of the chorda dorsalis to the nucleus pulposus. Our study firmly establishes a focal real chondrocytic phenotype of neoplastic cells in chordomas. Chondroid chordoma is neither a low-grade chondrosarcoma nor a misnomer as discussed previously.

Collagenous and basement membrane proteins of chordoma: immunohistochemical analysis

Tissue localization of collagenous and basement membrane proteins in the extracellular matrix of five sacro-coccygeal chordomas and human fetal notochords was examined immunohistochemically to assess the implications for the histogenesis and histological diagnosis of chordoma. Human fetal notochords and conventional chordomas both exhibited basement membrane proteins (such as type IV collagen and laminin) and type VI collagen on the surfaces of cellular cords. Type II collagen, a main structural protein of cartilage, was also present in both tissues. In the chordomas, however, type II collagen was not so widespread as it was in the notochords, and the predominant collagenous protein was type I. In contrast, an altered deposition of these proteins was noticed in a recurrent tumour which, histologically, showed considerable atypia and eventually metastasized to the liver. The characteristic cartilage-type and basement membrane proteins disappeared and unusual collagen types, such as types III and V, appeared in the stroma. The results further support the notochordal origin of chordoma and suggest that the immunohistochemistry of collagenous and basement membrane proteins may be a helpful criterion for the histological diagnosis and prediction of the biological aggressiveness of chordomas.

Superior localisation and imaging of radiolabelled monoclonal antibody E48 F(ab')2 fragment in xenografts of human squamous cell carcinoma of the head and neck and of the vulva as compared to monoclonal antibody E48 IgG

Monoclonal antibody (MAb) E48 and its F(ab')2 fragment, radiolabelled with 131I, were tested for tumour localisation and imaging in nude mice bearing a squamous cell carcinoma xenograft line derived from a head and neck carcinoma (HNX-HN) or from a vulva carcinoma (VX-A431). MAb IgG or F(ab')2 fragments were injected in parallel and at day 1, 2, 3 and 6 or 7, mice were either scanned with a gamma camera or dissected for determination of isotope biodistribution. In HNX-HN bearing mice, E48 IgG as well as F(ab')2 showed highly specific localisation in tumour tissue. The mean tumour uptake (n = 4) expressed as the percentage of the injected dose per gram of tumour tissue (percentage ID/g) of IgG was 11.9% at day 1 and increased to 14.6% at day 6 whereas percentage ID/g of F(ab')2 was 7.2% at day 1 and decreased during subsequent days. Tumour to blood ratios (T/B) at day 1 were 1.2 for IgG and 13.6 for F(ab')2 and reached a maximum at day 6 with values of 6.4 and 54.2 respectively. In VX-A431 bearing mice, only E48 F(ab')2 showed preferential localisation in tumour tissue. At day 1, Percentage ID/g of IgG was 3.7 and T/B was 0.3, while percentage ID/g of F(ab')2 was 2.4 and T/B was 3.2. Percentage ID/g decreased after day 1 while T/B increased. In these experiments no preferential localisation of either isotype matched 125I-labelled control IgG or F(ab')2 was observed. In F(ab')2 injected HNX-HN bearing mice as well as VX-A431 bearing mice, tumours could be visualised at day 1 and 2 without any appreciable background activity. With MAb IgG this was also possible in HNX-HN bearing mice (but not in VX-A431 bearing mice) but only at day 3 and 6. These findings suggest that the superior tumour to non-tumour ratios render the E48 F(ab')2 fragment more qualified for specific targeting of radioisotopes to tumour xenografts in this experimental setting.

The nature of cytoplasmic vacuoles in chordoma cells. A correlative enzyme and electron microscopic histochemical study

Enzyme histochemical study revealed that a sacrococcygeal chordoma not only was rich in oxidoreductive enzymes but also in the enzymes (phosphorylase, hexokinase, phosphoglucomutase, glucose phosphate isomerase and UDP-glucose dehydrogenase) leading to the synthesis of stromal glycosaminoglycans from glycogen. UDP-glucose dehydrogenase is particularly important in oxidizing UDP-glucose to UDP-glucuronic acid, the building block of hyaluronic acid and chondroitin sulfates. These enzymatic activities were consistent with the ultrastructural findings of abundant membrane-bound glycogen as well as large intracytoplasmic vacuoles with occasional residual glycogen particles. Furthermore, ultrastructural histochemical study using high iron diamine (HID) specifically localized the sulfated glycosaminoglycans (SG) extracellularly as well as intracellularly in distended Golgi saccules and 187-320 nm mature secretory vesicles. No HID staining was noted in the large intracytoplasmic vacuoles or rough endoplasmic reticulum. This study not only supports the hypothesis that the vacuoles of physaliphorous cells are the result of breakdown and utilization of membrane bound glycogen in the biosynthesis of SG, but also demonstrates that intracellular synthesis and storage of SG in chordoma are not in large vacuoles as previous investigators have believed.

Chordoma: an immunohistologic study

Fourteen chordomas, five myxoid chondrosarcomas, and 15 chondroid tumors (four mesenchymal and 11 conventional chondrosarcomas) were stained for cytokeratin, S-100 protein, carcinoembryonic antigen (CEA), and vimentin. The epithelial markers stained 93 per cent of the chordomas, whereas none of the tumors of other types showed any staining. Sixty-four per cent of the chordomas, 20 per cent of the myxoid chondrosarcomas, and 87 per cent of the other chondroid tumors were positive for S-100 protein. All of the tumors were positive for vimentin. Three of the 14 chordomas were positive for CEA. The present study confirms the utility of these markers in the differential diagnosis of chordoma and tumors with similar histologic characteristics.

Orbital invasion by an intracranial chordoma

A 26-year-old woman experienced bilateral hearing loss, progressive nasal obstruction, and rhinorrhea. Examination disclosed a retropharyngeal mass. A needle biopsy specimen of the mass showed that it was a chordoma. The patient underwent surgery to remove the mass and received a postoperative course of radioactive cobalt. She did well for 18 months, at which time proptosis gradually developed in her right eye. Although the optic nerve heads and visual fields appeared normal, roentgenograms showed a large lesion involving the anterior and middle cranial fossae and destruction of the right posterior ethmoid sinus and right superior orbital fissure. Shortly after completing a course of methotrexate therapy (total dose, 89 mg), the patient experienced sudden pain and visual loss in her right eye. Surgical decompression of the orbit failed to restore light perception. The following year, her left eye became involved. A transfrontal craniotomy and extradural orbital decompression provided only temporary improvement. Four months later, left lateral rectus muscle palsy developed and her visual acuity decreased to 6/60 (20/200). Radiation therapy (400 rads per week; total dose, 3,200 rads) and treatment with methotrexate, vincristine sulfate, and prednisone did not improve her condition. At the time of her death, six years after the first symptom appeared, the patient was blind in both eyes, almost completely deaf, and suffered from severe dysphagia.

A comparative ultrastructural study of chondrosarcoma, chordoid sarcoma, and chordoma

A morphologic and electron microscopic study was made of two chordoid sarcomas. These lesions were compared with two classical chondrosarcomas and two chordomas. These chondrosarcoma cells showed many features common to chondrocytes, such as abundant RER, well-developed Golgi complexes, and microvillous cytoplasmatic membranes. The chordoid sarcomas bore a close morphologic resemblance to the chordomas but the ultrastructural features revealed a close relationship to the chondrosarcomas. The chordoid sarcoma and chondrosarcoma cells had scalloped cytoplasmatic membranes, variable amounts of glycogen, round or oval nuclei and microfibrils, collagen, and electron-dense granules in the ground substance. The chordoma was characterized by the presence of stellate and physalipherous cells, as well as many transitional cells, with varying nuclear morphology; dilated and irregular RER in contact with mitochondria and morphologically varied vacuoles are the main features in the cytoplasm. This study suggests that chordoid sarcoma represents a variety of the chondrosarcoma rather than a form of chordoma. These findings also support the suggestion of Weiss that chordoid sarcoma is an extraskeletal myxoid chondrosarcoma.