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

EM proves invaluable in the confirmation of chordoma in the sacral mass of a middle-aged man

A case of a 47-year-old male with a sacral spine mass was investigated by histology, immunohistochemistry (IHC), and electron microscopy (EM). The light microscopy of the first core biopsy revealed scant cellularity with spindle and round cells with eosinophilic cytoplasm within a fibromyxoid background. Immunostaining with pancytokeratin, cytokeratin 19, and S100 was nonspecific. Another biopsy was attempted to obtain a more definitive diagnosis. Light microscopy of the second core had scant cellular material. However, the tissue was specifically requested for ultrastructural evaluation and revealed features diagnostic of chordoma. After definitive diagnosis, radical resection of the mass was performed. This case illustrates how EM was instrumental in the definitive diagnosis before radical resection in a case that was not clear by hematoxylin and eosin (H&E) and IHC alone.

Pathobiology of selected tumors of the base of the skull

Skull base surgery is a new subspeciality, and, up to this point, most articles on this subject have focused on innovative operative-reconstructive approaches to tumors in this region. It is now important that we embark on a new era, the era of tumor biology, and concentrate on new ways of evaluating these neoplasms from a pathologic viewpoint. The hematoxylin-cosin section is no longer an end point, but just a beginning. This is the age of molecular biology. It is important that these tumors be evaluated, either prospectively or retrospectively, employing immunohistochemical staining, flow cytometry, oncogene expression, cytogenetics, or other techniques in order to identify important prognostic features. Data from these additional studies may then be used to develop new treatment strategies. Skull base societies should develop protocols for one or more of these tumors to ensure that they are indeed evaluated uniformly. In this article I emphasize the importance of accurate histologic classification or subclassification of these neoplasms and focus on contemporary parameters that may or may not impact on prognosis.

Base of Skull Chordomas in Children and Adolescents

Chordomas in children and adolescents comprise <5% of all chordomas and most frequently develop in the skull base. These tumors are believed to behave more aggressively than chordomas in adults and may have unusual morphology. This study examines a large series of pediatric skull base chordomas treated with a standardized protocol to characterize the behavior and morphology of these tumors. There were 31 males and 42 females ranging from 1 to 18 (mean 9.7) years. Forty-two cases (58%) were conventional chordomas, some of which had unusual histopathologic features. Chondroid chordomas comprised 23% of cases. Fourteen tumors (19%) were highly cellular and had a solid growth pattern with no myxoid matrix or lobular architecture. Eight of these had cytologic features of conventional chordoma cells including physaliferous cells (cellular chordoma). The remaining cellular tumors were composed of poorly differentiated epithelioid cells set in a fibrous stroma and lacked physaliferous cells (poorly differentiated chordoma). All variants studied by immunohistochemistry showed positive staining for cytokeratin, epithelial membrane antigen, S100 protein, and vimentin. Mitoses and necrosis were seen in all variants. Follow-up data were available for all patients and ranged from 1 to 21 (mean 7.25) years. The survival rate was 81%. All but 1 patient with poorly differentiated chordoma died of disease. Overall, base of skull chordomas in children and adolescents treated with proton beam radiation have better survival than chordomas in adults. However, poorly differentiated chordomas are highly aggressive tumors.

Soft tissue sacrococcygeal chordoma with intracytoplasmic filamentous inclusions

Extraskeletal chordoma arising within soft tissue is a rare occurrence. We report a case of chordoma that is unusual both for its location within the subcutaneous soft tissue of the sacrococcygeal region without involvement of adjacent bones and for the presence of eosinophilic roundish inclusion bodies within the cytoplasm of tumor cells. These bodies revealed immunoreactivity for cytokeratin and a fibrillar, partly whorled structure on the electron microscopic examination, consistent with an intermediate filament-based composition. To our knowledge, this is the first report of chordoma featuring this cellular change although we do not know the significance of these bodies.

Extraskeletal myxoid chondrosarcoma: a light microscopic, immunohistochemical, ultrastructural and immuno-ultrastructural study indicating neuroendocrine differentiation

AIMS

Extraskeletal myxoid chondrosarcoma is a rare low-grade soft-tissue sarcoma with locally aggressive and metastasizing potential. Extraskeletal myxoid chondrosarcoma has distinctive clinical, light microscopic, immunophenotypic, cytogenetic and ultrastructural features. Evidence that extraskeletal myxoid chondrosarcoma often shows neuroendocrine features was first provided by Chhieng et al. on the basis of an immunohistochemical and ultrastructural study of seven cases. Our study aims to further confirm by immunohistochemistry and ultrastructural studies, including immunoelectron microscopy, that extraskeletal myxoid chondrosarcoma indeed may show neuroendocrine differentiation.

METHODS AND RESULTS

Fifteen cases of extraskeletal myxoid chondrosarcoma and seven control cases of skeletal chondrosarcomas were studied. Extensive immunohistochemical analysis was performed in all cases and ultrastructural studies were done in 11 extraskeletal myxoid chondrosarcomas and three skeletal chondrosarcomas. Immunoelectron microscopy was performed on one case each of extraskeletal myxoid chondrosarcoma and skeletal chondrosarcoma. Extraskeletal myxoid chondrosarcomas expressed neuron-specific enolase (100%), synaptophysin (87%), S100 (50%), PGP 9.5 (40%), and epithelial membrane antigen (25%). Co-expression of synaptophysin and PGP 9.5 was observed in six tumours. Skeletal chondrosarcomas showed expression of S100 protein, vimentin and neuron-specific enolase in all cases. Synaptophysin, chromogranin and PGP 9.5 were not expressed in any skeletal chondrosarcoma case. Ultrastructurally, extraskeletal myxoid chondrosarcoma was characterized by distinct cords of cells immersed in a glycosaminoglycan-rich matrix. The cells were rich in mitochondria, had well-developed Golgi apparatus and there were numerous smooth vesicles. In three cases there were easily found 140-180 nm diameter membrane-bound dense-core granules in cell bodies and in processes, unrelated to the Golgi, compatible with neurosecretory granules. Fewer such granules were present in the remaining extraskeletal myxoid chondrosarcoma cases, three of which also contained intracisternal tubules typical of extraskeletal myxoid chondrosarcoma. The skeletal chondrosarcomas had scalloped cell surfaces, prominent rough endoplasmic reticulum focally distended with secretory product, and lacked neurosecretory granules. Intermediate filaments were prominent in both extraskeletal myxoid chondrosarcoma and skeletal chondrosarcomas. Immunoelectron microscopy showed synaptophysin expression in the extraskeletal myxoid chondrosarcoma but not in the skeletal chondrosarcoma case.

CONCLUSIONS

This study confirms that a substantial proportion of extraskeletal myxoid chondrosarcomas show immunophenotypic and/or ultrastructural evidence of neuroendocrine differentiation, and are unlikely to be related to conventional skeletal chondrosarcomas.

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.

Chordoma periphericum: a case report

The authors describe a tumor that had the histologic and ultrastructural features and immunohistochemical profile of an axial chordoma, but arose in the distal ulna. A skeletal survey failed to show any other site of involvement. The tumor was resected, and the patient remains free of disease 2 1/2 years later. Rare tumors with the histologic features of chordoma have been reported in appendicular locations. Chordoma periphericum, a tumor that has the potential to metastasize, needs to be distinguished from parachordoma because no classic parachordoma has been reported to disseminate.

Extraskeletal myxoid chondrosarcoma: a clinicopathologic, immunohistochemical, and ploidy analysis of 23 cases

Twenty-three cases of extraskeletal myxoid chondrosarcoma, evaluated at the Mayo Clinic between 1968 and 1996, were studied for clinicopathologic features, immunohistochemical profile, Ki-67 activity, and ploidy status to identify adverse prognostic factors. Females and males were equally affected, and the median age at diagnosis was 50 years. The tumors were located mainly in the lower extremities (83%), and the median tumor size was 9.5 cm. Sixteen tumors showed low cellularity (70%), and eight tumors had high mitotic activity (more than two per 10 high-power fields). The tumors were immunoreactive for vimentin (89%), synaptophysin (72%), epithelial membrane antigen (28%), and S-100 protein (17%). Nine tumors were diploid, three aneuploid, and one tetraploid. Mean Ki-67 activity was 11% (range, 1 to 45%). The 10-year overall survival rate was 78%. On univariate analysis, tumor size > or = 10 cm, high cellularity, presence of anaplasia or rhabdoid features, mitotic activity more than two per 10 high-power fields, Ki-67 > or = 10%, and Ki-67 "hot spot" > or = 25% were associated with decreased metastasis-free or overall survival. Ploidy status was not associated with any adverse outcome. The presence of any of these adverse prognostic factors can indicate the possibility of a more aggressive behavior in extraskeletal myxoid chondrosarcoma, and a closer follow-up is suggested.

National cancer database report on chondrosarcoma of the head and neck

BACKGROUND

Management of chondrosarcoma of the head and neck is largely based on single-institution reports with small numbers accrued over several decades.

METHODS

The American College of Surgeons' National Cancer Data Base included 400 cases of chondrosarcoma of the head and neck diagnosed between 1985 and 1995. Chi square analyses of selected contingency tables and Wilcoxon regression analyses of selected survival stratifications were performed.

RESULTS

Histologic types included conventional (80.8%), myxoid (10.5%), and mesenchymal (8.8%). The mesenchymal and myxoid subtypes were rare among white patients (17.1%) and more common among African-American (31.8%) and Hispanic patients (44.9%). Treatment was most commonly surgery alone (59.5%) and surgery with irradiation (21.0%). Disease-specific survival was 87.2% at 5 years and 70.6% at 10 years. Worse 5-year survival was associated with higher grade (67.3%), regional or distant spread (71.0%), and the myxoid (45.0%) or mesenchymal (53.2%) subtypes.

CONCLUSIONS

Chondrosarcoma of the head and neck encompasses a variety of lesions that differ substantially by demographic and tumor characteristics. Individual tumors can be classified further according to site of origin, histologic subtype, and tumor grade, which can be used to predict biologic behavior and prognosis.

High-grade extraskeletal myxoid chondrosarcoma: a high-grade epithelioid malignancy

AIMS

Extraskeletal myxoid chondrosarcoma is typically a low-to-intermediate grade sarcoma that is associated with a prolonged clinical course. High-grade forms are rare and not well characterized. In this series we report the clinicopathological, immunohistochemical and ultrastructural findings in four cases of high-grade extraskeletal myxoid chondrosarcoma.

METHODS AND RESULTS

The patients were three men and one woman (ages 34-73 years) with tumours located in the thigh (two cases), paraspinal soft tissue and perineum. Three patients had metastases, one at 12 weeks, one at 10 months, and one at presentation of recurrent tumour. In the latter case the original tumour was low grade and became high grade when it recurred 3.5 years later. All three patients died of disease. One patient was lost to follow-up. The most striking histological feature in all four tumours was the presence of numerous large epithelioid cells. These cells were arranged in cords within myxoid matrix and in sheets devoid of matrix. Two tumours had areas of conventional extraskeletal myxoid chondrosarcoma intermixed with the high-grade areas. One tumour showed transition to high-grade spindle cell sarcoma. One tumour had cells with rhabdoid features. Immunohistochemically, two tumours focally expressed S100 protein, and one focally expressed EMA. All were negative with cytokeratin, desmin, smooth muscle actin, HMB45, CD31 and CD34. Ultrastructural features in three cases were compatible with chondrosarcoma; one tumour had aggregates of microtubules within rough endoplasmic reticulum, a characteristic feature of this tumour.

CONCLUSIONS

High-grade extraskeletal myxoid chondrosaroma is a rare and aggressive soft tissue sarcoma, and should be included in the differential diagnosis of other epithelioid malignancies.

Cutaneous parachordoma. A light microscopic and immunohistochemical report of two cases and review of the literature

Parachordomas are rare cutaneous tumors that show virtually identical histologic findings to chordomas. Therefore, the major differential diagnosis in a case of parchordoma is metastatic chordoma. Parachordomas are benign neoplasms and most often develop on the extremities adjacent to tendons, synovium or osseous structures, as opposed to chordomas, which are malignant tumors located along the craniospinal axis. While recurrences may occur in cases of parachordoma, metastases have not been reported. In this report, two cases of parachordomas are reported and the literature reviewed. By light microscopy, parachordomas show eosinophilic bands of fibrous tissue separating lobules of cells with variably vacuolated cytoplasm (physaliphorous cells) admixed with more epithelioid cells in a myxoid stroma. Parachordomas and chordomas share immunohistochemical and ultrastructural features. Both stain with S-100 protein and vimentin, and ultrastructurally both demonstrate cytoplasmic vacuoles, intermediate filaments, pinocytotic vesicles, celljunctions, and cytoplasmic membranes with microvillous processes. Chordomas more frequently express cytokeratin (98% vs. 66% in parachordomas) and epithelial membrane antigen (90% vs. 20% in parachordomas) and chordomas have a larger number of rough endoplasmic reticulum-mitochondrial complexes. Thus, positive staining with epithelial membrane antigen and the identification of a large number of rough endoplasmic reticulum-mitochondrial complexes are suggestive of metastatic chordoma. However, the definitive distinction remains a clinical one after appropriate radiologic studies of the skull and spinal chord.

Parachordoma. A case report of a very rare soft tissue tumor

An extremely rare and peculiar soft tissue tumor is described. Few examples of this tumor are classified under the term parachordoma, while probably many more are designated as chordoid sarcomas. The tumor presents histological features similar to those of chordoma, as well as to extraskeletal myxoid chondrosarcomas (chordoid sarcomas), and should also be differentiated from chondroid syringoma or mixed tumor of the skin. The tumor reported herein appeared as a deep cited soft tissue mass, presenting the histology of chordoma in an extra-axial localization. On the other hand, the positive immunoreactions of the tumor cells with cytokeratin and epithelial membrane antigen (EMA) ruled out the diagnosis of chondrosarcoma. It seems, therefore, that this is a special type of soft tissue tumor with bimodal differentiation (epithelial and mesenchymal) with good prognosis.

Chordomas of the mediastinum: clinicopathologic, immunohistochemical, and ultrastructural study of six cases presenting as posterior mediastinal masses

Six cases of chordomas presenting as primary posterior mediastinal tumors are described. Three patients were female, and three were male between the ages of 8 and 65 years (mean, 40.6 years). In all cases, the tumors presented radiographically as relatively well-circumscribed, encapsulated soft tissue masses that did not seem to be related to the thoracic or dorsal spine. Only in one case, focal infiltration of bone at the level of T6-T7 was observed at the time of surgery. Histologically, the lesions showed a spectrum of features that ranged from sheets and cords of large cells with abundant vacuolated cytoplasm to small, stellate cells embedded within an abundant mucoid matrix. In one case, the cell population showed more pronounced nuclear atypia with loss of cytoplasmic vacuolization, frequent mitotic figures, necrosis, and solid areas characterized by a perivascular distribution of atypical spindle cells set against a myxoid stroma. Another case showed features of chondroid chordoma, with an immature chondroid-appearing matrix surrounding the atypical tumor cells. Immunohistochemical studies in all cases showed positive staining of the tumor cells with CAM 5.2 and broad-spectrum keratin, epithelial membrane antigen (EMA) and vimentin, and, to a lesser extent, with S-100 protein. Stains for muscle actin, carcinoembryonic antigen (CEA), and desmin were negative. Ultrastructural examination in two cases showed a spectrum of features that varied from large cells with abundant cytoplasm containing scattered ribosomes, glycogen granules, Golgi apparatti, abundant intermediate filaments, and small lumen formation with immature microvilli to smaller cells with elongated cytoplasmic processes, fewer intermediate filaments, rare desmosome type intercellular junctions, and complexes of mitochondria/rough endoplasmic reticulum. On clinical follow-up, two patients died with metastases to the lungs, chest wall, and liver from 1 to 3 years after diagnosis, and two patients are alive and well without evidence of disease after 3 and 16 years. Chordoma should be entertained in the differential diagnosis of posterior mediastinal tumors. Application of immunohistochemical stains or electron microscopy will be of aid in separating them from other conditions that may histologically closely resemble these lesions.

Chordoid tumor: a light, electron microscopic, and immunohistochemical study

Chordoid tumor--synonymous with chordoid sarcoma, parachordoma, and peripheral chordoma--is a very rare neoplasm with histologic similarity to chordoma that is found outside the axial skeleton. A soft tissue chordoid tumor in the gluteus maximus muscle of a 42-year-old man is presented. This tumor had morphologic features identical to a chordoma: nodular growth with vacuolated cytoplasm and myxomatous stroma by light microscopy, positive immunoreaction for cytokeratin and epithelial membrane antigen by immunohistochemistry, desmosomes, intercellular lumina lined with microvilli, and the presence of basal lamina material by electron microscopy. Two similar cases have been reported in the English literature.

Mitochondria-rough endoplasmic reticulum complexes in a malignant fibrous histiocytoma

Mitochondria-rough endoplasmic reticulum complexes identical to the ones usually found in chordoma were frequently observed in tumors cells of a malignant fibrous histiocytoma arising in the left thigh of a 48-year-old woman. Although the significance of these structures is unknown, this finding is consistent with the known transformation of chordoma into malignant fibrous histiocytoma.

Chordoma cutis: a report of nineteen patients with cutaneous involvement of chordoma

BACKGROUND

Chordoma, an uncommon tumor originating from remnants of the notochord, with cutaneous involvement has rarely been reported.

OBJECTIVE

Our purpose was to document clinical manifestations, histopathologic features, immunohistochemical findings, treatment, and course of chordoma with cutaneous involvement.

METHODS

Pathologically proven cases of chordoma were reviewed retrospectively for cutaneous involvement. Detailed clinical data and histopathologic changes were studied. Skin biopsy specimens were stained for immunohistochemical phenotyping.

RESULTS

Of 207 cases of chordoma, 19 had skin involvement: as local recurrences or metastasis in 12, as direct extension of primary tumor in 6, and as a result of distant metastasis from sacrococcygeal chordoma in 1. Local recurrences were frequent, but distant metastasis to various organs, including skin, occurred.

CONCLUSION

We propose the term chordoma cutis to describe this condition. In seven patients, cutaneous lesions were detected when the diagnosis of primary chordoma was made.

Chordomalike soft tissue sarcoma in the leg: a light and electron microscopic and immunohistochemical study

A soft tissue tumor in the leg of a 67-year-old woman is described. This large tumor below the knee area infiltrated extensively the deep and superficial soft tissues but did not involve the bones. The tumor cells formed nodules resembling the architecture seen in chondroid tumors and chordoma. The tumor cells were often vacuolized, and there was extracellular myxoid matrix similar to that in chordoma or myxoid chondrosarcoma. Immunohistochemistry showed keratins 8 and 19, epithelial membrane antigen, and vimentin in most tumor cells, and there was also S-100 protein positivity in a number of tumor cells. Electron microscopy showed desmosomelike cell junctions and bundles of intermediate filaments resembling those seen in many epithelial neoplasms. Thus the tumor resembled chordoma in many respects. Because clinically no other primary tumor was found, this tumor is probably a chordomalike primary soft tissue sarcoma different from typical extraskeletal myxoid chondrosarcoma or chordoid sarcoma.

Classical and chondroid chordoma. A light-microscopic, histochemical, ultrastructural and immunohistochemical analysis of the various cell types

The aim of the present investigation was to characterize the various cell types of classical and chondroid chordomas. Eight cases of classical chordoma, 1 case of sacrococcygeal chordoma with chondroid areas and 2 cases of spheno-occipital chondroid chordoma were studied. Ultrastructurally and immunohistochemically (immunoreactivity for cytokeratins, epithelial membrane antigen [EMA], tissue polypeptide antigen [TPA] and human milk fat globule protein [HMFG]) the 3 cell types (physaliferous, epithelial-like, and spindle-shaped) recognized light-microscopically presented features of epithelial differentiation and rather formed a continuous spectrum than being distinct cell types. The chondroid areas of the chondroid chordomas had similar ultrastructural and immunohistochemical properties except for the lack of immunoreactivity for EMA and HMFG. The results of the critical electrolyte concentration technique according to Scott and Dorling indicated that there was no difference in the sulfated glycosaminoglycan content between classical and chondroid chordomas: all the tumors contained chondroitin sulfate. The presence of chondroitin sulfate, immunoreactivity for vimentin and S-100 protein and areas of cartilaginous differentiation in three cases indicate a relationship both to chondromatous tumors and to normal notochord, from which chordoma is believed to originate.

Expression of different cytokeratin subclasses in human chordoma

A detailed immunohistochemical characterization of different cytokeratin subclasses was performed on frozen tumour tissue from three classical chordomas. Simple epithelium cytokeratins Nos 8, 18, and 19 were detected in all tumour cells while cytokeratin No. 7 was not found. Cytokeratins characteristic of squamous differentiation, including keratinization, were generally lacking, with the exception of the varying expression of cytokeratin No. 4. Vimentin was found in all the tumours, while they lacked desmin immunoreactivity. The present study indicates the co-expression of vimentin and cytokeratins, predominantly of the simple epithelium type. In addition, chordoma cells have the ability to express cytokeratins characteristic of squamous differentiation. This finding corresponds well to the electron microscopic findings of tonofilament bundles ending in well-developed desmosomes.

Primary extraskeletal mesenchymal chondrosarcoma of the lid

A 15-year-old girl presented with a painless nodule in the nasal lower-lid portion of the left eye at the beginning of 1989. The tumor was excised in March 1989, and the histopathologic diagnosis was - erroneously - a chondromatous choristoma of the lid. The tumor recurred within several weeks. Another excision was performed, which led to the diagnosis of a malignant mesenchymal chondrosarcoma of the lid. Histopathology revealed the typical bimorphic pattern, with well-differentiated chondrocytes being surrounded by small anaplastic cells. The tumor cells stained positive for S100-protein and vimentin, were negative for cytokeratin and were studied ultrastructurally. Radical excision and adjuvant chemotherapy were performed in our patient; at 18 months after the onset of tumor growth, she is free of local or general tumor recurrence. To our knowledge, primary mesenchymal chondrosarcoma has not previously been described in the lid area.

Microtubular aggregates in the rough endoplasmic reticulum of sacrococcygeal chordoma

A tumor with the light microscopic and immunohistologic characteristics of chordoma in the sacrococcygeal region in a 48-year-old man was examined by electron microscopy and immunohistochemistry for tubulin. A large population of cells exhibited prominent parallel arrays of long, straight microtubules in the rough endoplasmic reticulum in addition to the well-described ultrastructural features of chordoma. Immunoreaction to tubulin recognized in the juxtanuclear regions of the large number of tumor cells was in accordance with the ultrastructural localization of the microtubular aggregates. This seems to be the first report of microtubular aggregations in rough endoplasmic reticulum in classic chordoma. Furthermore, the present electron microscopic and immunohistochemical findings suggest that tubulin is a constituent of the unusual structures.

Immunohistochemical investigation of chordomas: histogenetic and differential diagnostic aspects

Chordomas are rare tumors of neuroectodermal origin and often show a very heterogeneous histological picture. In a combined histochemical and immunohistochemical study of 32 chordomas collected in the Bone Tumor Registry of Westphalia we were able to show that the immunoreactivity of the cells in both chordoma and notochordal structures are in close relationship with the extracellular matrix and depends more on the metabolic activity of these cells than on the origin of the cells of the neuroectoderm. All tumor cells show a bimodal immunoreaction with cytokeratin and vimentin, as well as a strong immunoreaction with the oncofetal markers CEA and AFP. The differentiation of chordomas from other malignant tumors, mainly the myxoid variant of chondrosarcoma, may cause major difficulties, especially if only a little biopsy material is available. Here we can see that in tumors with bimodal immunoexpression of vimentin and cytokeratin, as can be found in chordomas, the further use of antibodies offers a reliable differential diagnostic tool. The positive reaction of chordomas with all epithelial tumor markers offers a clear differentiation from chondrosarcomas, which, unlike chordomas, do not express cytokeratin. The identification of a marker profile by employing common antisera is of major value in the differentiation of chordoma from other epithelial or mesenchymal tumors.

Extraskeletal myxoid chondrosarcoma characterized by microtubular aggregates in the rough endoplasmic reticulum and tubulin immunoreactivity

A case is reported of a 66-year-old female with an extraskeletal myxoid chondrosarcoma which had originated in the lateral region of the right knee. The tumour tissue of the primary, recurrent, and metastatic deposits in the lungs was examined by electron microscopy and immunohistochemistry. Almost all the sarcoma cells in every tumour specimen harboured immunoreactivity to both alpha- and beta-subunits of S-100 protein. A large population of cells in the subcutaneous tumour at autopsy had numerous parallel arrays of microtubules within the rough endoplasmic reticulum in addition to the well-described ultrastructural features indicative of chondroblastic origin. These structures were present in round to polygonal, but not in fibroblastic, tumour cells. Tubulin immunoreactivity in the tumour cells showed the same tendency, being frequently positive in the large cells of the subcutaneous tumour but weakly positive in the fibroblastic and medium-sized cells of the recurrent and metastatic tumours. The parallel arrays of intracisternal microtubules therefore may be composed of tubulin protein, as in ordinary cytoplasmic microtubules.

Chordomas in Fischer 344 rats

Tissue sections and records of 56 rats with chordoma, identified in the National Toxicology Program's (NTP) data base of approximately 115,000 rats, were examined to determine morphological characteristics, incidence, and aspects of biological behavior. Chordomas occurred in aged rats, originated predominantly in lumbosacral vertebrae, were highly malignant, occurred three times more often in male versus female rats, and commonly produced bilateral posterior paresis, paralysis, and/or distention of the colon and rectum.

Does chondroid chordoma exist?

The existence of chondroid chordoma (CC), initially described in 1973, has remained controversial. Since the antigenic profiles of both chordoma (CD) and cartilaginous (chondroid) lesions have been well characterized, we decided to study chondroid chordoma immunohistochemically. Our hypothesis was that chondroid chordoma should display a hybrid or mixed pattern of staining: chordomatous areas with an epithelial phenotype and cartilaginous areas with a mesenchymal (non-epithelial) phenotype. An analysis of CC (seven cases) was performed and compared with results obtained on notochord, cartilage, classic CD (18 cases), peripheral chondromas (two cases), and peripheral chondrosarcomas (CS, eight cases). Four epithelial markers were employed: MKER and AE-1 (both monoclonal antibodies to cytokeratin); PKER (a polyclonal antibody to cytokeratin); and, EMA (epithelial membrane antigen). In addition, selected cases were tested for the presence of neurofilament (NF) and glial fibrillary acidic protein (GFAP). All 18 CD's exhibited the expected epithelial immunophenotype - MKER+, AE-1+, PKER+, and EMA+ - a reaction pattern nearly identical to that found in fetal notochord. This reinforced the importance of the growth pattern in assessing the presence of chordomatous elements. All chondromas and CS's failed to express any of the epithelial markers studied and contained only S-100 immunoreactivity, like cartilage. Chondroid chordoma resembled cartilaginous tumors immunohistochemically; no mixed pattern with even focal epithelial marker reactivity was identified. All CC tested were also NF and GFAP negative. We conclude that CC either does not exist or is extremely rare and that these tumors are cartilaginous in nature.(ABSTRACT TRUNCATED AT 250 WORDS)

Extraskeletal myxoid chondrosarcoma: a histochemical and immunohistochemical study

In reviewing a large series of soft tissue sarcomas, nine cases of extraskeletal myxoid chondrosarcoma have been retrieved. These tumours, which principally presented in middle-aged adults, have been examined histochemically to determine the heteroglycan content of their myxoid matrix and immunohistochemically for the presence of S-100 protein. The principal mucopolysaccharides identified were chondroitin-4 and 6-sulphate and keratan sulphate; each of the tumours was S-100 positive. The relevance of these findings to the histogenesis and differential diagnosis of these uncommon neoplasms is discussed.

Skull base chordoma with cavernous sinus involvement. Partial or radical tumour-removal?

A report of eight cases of skull base chordoma is given and the related literature reviewed. From disappointing experience with incomplete tumour removal and radiation the conclusion is drawn, that radical tumour removal at the first attempt should be strived for, even if the operative risk seems to be high. Cavernous sinus invasion should not be a reason to omit operation. Loss of function of one eye appears to be justified if radical tumour removal can be achieved. Possibly, the operative strategy can be improved by combining a frontal transbasal with a frontotemporal subtemporal approach, thus creating a chance for preservation of oculomotor function even in patients whose tumour has invaded the cavernous sinus region.

Nonepithelial tumors of the nasal cavity, paranasal sinuses, and nasopharynx. A clinicopathologic study. XIV: Chordomas

Twenty cases of a rare tumor, chordoma involving the nasal cavity, paranasal sinuses, or nasopharynx, are reported. Patients most often had localized headache, nasal obstruction, decreased hearing, or symptoms related to cranial nerve involvement, especially diplopia. A mass bulging into the nasopharynx, posterior nasal cavity, or pharynx was found on physical examination in 13 of these 20 patients, and in another 6 patients on radiologic examination. Paralysis of one or more cranial nerves was identified in the majority of patients who had tumors involving the upper nasopharynx. On radiologic examination, bone destruction was frequently identified in the clivus and sphenoid areas, and less commonly in the cervical vertebrae. Each patient had biopsy-proven tumor in the nasopharynx or sphenoid areas. Patients usually were treated by combinations of surgery and radiotherapy, in some cases leading to prolonged periods of apparent tumor control. Radiotherapy frequently resulted in regression of symptoms, sometimes lasting many months or years. A few tumors that involved mainly the lower nasopharynx were more amenable to surgical resection, in one case leading to apparent tumor control. In those cases with adequate follow-up information, most patients had either died of their disease or were living with recurrent or persistent inoperable tumor. Some patients lived for many months or years between recurrences or with known tumor, indicating that chordomas often are slowly growing neoplasms. The histologic features of these chordomas are described and illustrated, and the histopathologic differential diagnosis is discussed.

Non-conventional chondrosarcomas and chondrogenesis

Pattern formation in chondroid development is compared with growth models exhibited by mesenchymal and myxoid chondrosarcomas. The results reveal strong similarities between mesenchymal chondrosarcoma and normal chondrogenesis. The fine vascularization of the tumor lobules of myxoid chondrosarcoma is discussed in relation to chondroid differentiation. A common histogenetic approach to the interpretation and classification of these neoplasias is proposed.

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

The present study is based on electron microscopical examinations of 15 conventional chondrosarcomas, 1 clear cell chondrosarcoma, 3 mesenchymal chondrosarcomas, 2 so-called chordoid sarcomas (extraskeletal myxoid chondrosarcoma), 4 sacrococcygeal chordomas, 2 ecchordoses and 1 neoplasm of tibia with features of a true peripheral chordoma (parachordoma). The neoplastic cells from various types of chondrosarcoma shared a number of features with nonneoplastic chondrocytes as e.g. a well-developed rough endoplasmic reticulum and microvillous cytoplasmic processes. In clear-cell chondrosarcoma, glycogen accumulation in the tumour cells was a prominent feature. The cells of mesenchymal chondrosarcoma usually showed the characteristics of immature mesenchymal cells. In contrast, chordomas commonly contained physaliferous cells with two types of vacuoles in their cytoplasm. The first type can be most adequately characterized as intracytoplasmic pseudoinclusions of intercellular substance, whereas the other type, glycogen-containing, single membrane-bound vacuoles most probably correspond to autophagosomes (cytolysosomes). Only vacuoles of the first type were recorded in the so-called chordoid sarcoma. They were also seen in chondrosarcomas. In contrast, both types of vacuoles were identified in the above-mentioned tibial tumour which, in addition, showed even other cytological characteristics of chordoma. The findings presented here have demonstrated distinct structural relationships between chordoid sarcoma and chondrogenic tumours. On the other hand, our observation of the uncommon tibial neoplasm indicates the possibility that tumours identical with chordoma may occur at sites other than the axial skeleton.

Chordoid sarcoma (extraskeletal myxoid chondrosarcoma)

Evaluation of a series of 12 chordoid sarcomas suggests that there is a wider range of histological features in this entity then previously appreciated. Six of the lesions had a typical tumor cell organization and a mixture of cellular and myxoid stromal components, while the remaining cases were atypical because of a more solid growth pattern. Four of the 12 cases, that included both typically myxoid and more cellular examples, had small foci with hyalinized stroma segragating individual or small groups of tumor cells with and without lacunar spaces. Two atypical cases revealed more extensive and obvious chondrocytic differentiation in recurrent or metastatic lesions and in one of these, the histological pattern was that of mesenchymal chondrosarcoma. Ultrastructural examination of three cases revealed fine structural features of both the tumor cell population and extracellular matrix compatible with chondrocytic differentiation. Results of light and electron microscopy of this series of chordoid sarcoma add further support for categorizing this tumor with other malignant chondrocytic neoplasms. It is probable that chordoid sarcoma and extraskeletal myxoid chondrosarcoma represent the same entity and that this lesion has a close histogenetic relationship to mesenchymal chondrosarcoma.