Chondroid chordoma: a low-grade chondrosarcoma and its differential diagnosis

Skull base chondroid chordoma: atypical case manifesting as intratumoral hemorrhage and literature review

OBJECTIVE

Chondroid chordoma (CC) is a rare but commonest subtype of chordoma with little reported clinical information. The present study summarizes and updates present knowledge of CC.

METHODS

Literature search for demographic data and clinical appearance of cranial CCs except for those entirely confined to the sinonasal region.

RESULTS

A total of 48 English language papers published from 1968-2013 were retrieved describing 132 CCs as skull base tumors. The male-to-female ratio was 1:1. The mean age at diagnosis was 43 years, predisposing to the third to fifth decades of life. The clival (34%) and spheno-occipital (29%) regions were the most frequent sites of origin followed by the sellar (12%) and sphenoid (5%) regions. Intratumoral calcification and bony erosion were identified as the characteristic neuroimaging findings. Surgical resection by the transcranial, transsphenoidal, transnasal, transpharyngeal, or transpalatal route with or without adjuvant radiotherapy was the main treatment option. The initial treatment outcome was satisfactory in 82% of cases with considerably better prognosis compared with typical chordomas.

CONCLUSION

CC is a distinct entity to be discriminated from the typical type of chordoma. There are no distinguishing features on magnetic resonance imaging between CC and typical chordoma. Intratumoral calcification and concurrent bony erosion on neuroimaging should suggest the possibility of CC. Extensive surgical resection and adjuvant radiotherapy can achieve satisfactory outcome.

Brachyury, SOX-9, and podoplanin, new markers in the skull base chordoma vs chondrosarcoma differential: a tissue microarray-based comparative analysis

The distinction between chondrosarcoma and chordoma of the skull base/head and neck is prognostically important; however, both have sufficient morphologic overlap to make delineation difficult. As a result of gene expression studies, additional candidate markers have been proposed to help in separating those entities. We sought to evaluate the performance of new markers: brachyury, SOX-9, and podoplanin alongside the more traditional markers glial fibrillary acid protein, carcinoembryonic antigen, CD24, and epithelial membrane antigen. Paraffin blocks from 103 skull base/head and neck chondroid tumors from 70 patients were retrieved (1969-2007). Diagnoses were made based on morphology and/or whole-section immunohistochemistry for cytokeratin and S100 protein yielding 79 chordomas (comprising 45 chondroid chordomas and 34 conventional chordomas), and 24 chondrosarcomas. A tissue microarray containing 0.6 mm cores of each tumor in triplicate was constructed using a manual array (MTA-1; Beecher Instruments). For visualization of staining, the ImmPRESS detection system (Vector Laboratories) with 2-diaminobenzidine substrate was used. Sensitivities and specificities were calculated for each marker. Core loss from the microarray ranged from 25 to 29% yielding 66-78 viable cases per stain. The classic marker, cytokeratin, still has the best performance characteristics. When combined with brachyury, accuracy improves slightly (sensitivity and specificity for detection of chordoma 98 and 100%, respectively). Positivity for both epithelial membrane antigen and AE1/AE3 had a sensitivity of 90% and a specificity of 100% for detecting chordoma in this study. SOX-9 is apparently common to both notochordal and cartilaginous differentiation, and is not useful in the chordoma-chondrosarcoma differential diagnosis. Glial fibrillary acid protein, carcinoembryonic antigen, CD24, and epithelial membrane antigen did not outperform other markers, and are less useful in the diagnosis of chordoma vs chondrosarcoma. Podoplanin still remains the only positive marker for chondrosarcoma, though its accuracy is less than previously reported.

Dedifferentiated chordoma of the thoracic spine with rhabdomyosarcomatous differentiation. Report of a case and review of the literature

A case of spinal thoracic chordoma involving the T9 vertebra in a 70-year-old male patient, destroying the vertebral body and invading the vertebral canal with compression of the spinal cord, is presented. The patient was referred to our neurosurgical unit with a history of an irradiated metastatic adenocarcinoma to the thoracic vertebra, a diagnosis that was rendered 3 years earlier at another hospital on presentation. This misdiagnosis was likely due to the absolute rarity of thoracic vertebral chordomas (2%-3% of all chordomas), the higher frequency of metastatic deposits to the vertebrae from visceral cancers in the elderly, the limited amount of biopsy material available for histologic examination, and the epithelial phenotype of the tumor (keratin/EMA positive). The patient underwent second palliative surgery with subtotal piecemeal removal of the tumor bringing relief of the neurologic symptoms. The bulk of the tumor was represented by a high-grade pleomorphic sarcoma with adjacent areas of atypical chordoma. Small foci of conventional chordoma were also found. The previous histologic slides were also reviewed, which were consistent with the areas of atypical chordoma. Small targeted tissue fragments from areas of (atypical) chordoma and from sarcomatous areas were recovered for electron microscopy. The fine features of chordoma and focal rhabdomyoblastic differentiation were found with the latter retrospectively supported by immunohistochemical detection of striated muscle markers. A final diagnosis of dedifferentiated chordoma with rhabdomyoblastic differentiation was finally established. Rhabdomyoblastic metaplasia is a novelty in dedifferentiated chordoma. The patient died after 5 months. Autopsy was not requested.

D2-40 functions as an effective chondroid marker distinguishing true chondroid tumors from chordoma

Chordomas and low-grade chondrosarcomas of the central nervous system share many histological features, generating, at times, considerable diagnostic difficulty and, not infrequently, requiring immunohistochemical analysis for appropriate classification. While both chordomas and chondrosarcomas stain positively for S100, only chordomas typically express epithelial antigens like cytokeratins and epithelial membrane antigen. Positive or negative staining with these latter two markers currently represents the only immunohistochemical technique that effectively distinguishes chordomas from chondrosarcomas. A marker that is reliably positive in chondrosarcomas and negative in chordomas has, to date, not been reported. D2-40 is a monoclonal antibody initially developed against M2A, a fetal testis-related antigen now known as podoplanin (aggrus), which has been found to stain a diverse collection of both benign and malignant tissues. In this study, we systematically investigated D2-40 immunoreactivity in a series of 22 chordomas, 20 chondrosarcomas, and 12 enchondromas, in conjunction with cytokeratin and S100 immunostaining. We found that D2-40 robustly and reliably immunostains low-grade chondroid neoplasms (100% of enchondromas and 94% of grades I and II chondrosarcomas), but not chordomas. By contrast, we observed generally strong and diffuse cytokeratin positivity in all cases of chordoma, but not in cases of enchondroma or low-grade chondrosarcoma. Thus, we show that D2-40 behaves as a chondroid marker differentiating true chondroid neoplasms from chordoma. We also demonstrate D2-40 immunoreactivity in two cases of chordoid meningioma and, in doing so, tentatively provide a means to distinguish this tumor from chordoma.

Brachyury and chordoma: the chondroid–chordoid dilemma resolved?

Chordoma, and its relationship to the notochord, has intrigued many researchers over the last two centuries. In particular, the morphological overlap with cartilaginous tumours is striking, and developmental biology has shown a tight relationship between cartilage and the notochord. This is reflected in the expression of common genes in chordoid and chondroid tumours. Wide gene expression analyses have led to the identification of key molecules that might play a crucial role in the pathogenesis of chordoma. Brachyury, a key factor in notochord fate, is significantly differentially expressed in chordoma. This not only gives insight into the histogenesis of this tumour but may also point towards new diagnostic tools in the differential diagnosis between chordoid and chondroid tumours.

Skull base chordomas: overview of disease, management options, and outcome

Cranial base chordomas are locally invasive tumors that, from a midline, clival location, extend in different directions and display various patterns of skull base invasion. Although histologically benign, their invasive nature makes true “oncological” resection virtually impossible to achieve in most cases, despite modern skull base surgical techniques. Moreover, because of the tumor's location and proximity to critical neural and vascular structures, surgery-related morbidity can be significant when an aggressive resection is undertaken. Cytoreductive surgery assumes a critical role in the management of these lesions. The choice of surgical approach and the extent of resection are dependent on several factors: location and extension of the tumor, the surgeon's philosophy and familiarity with a specific approach, and the patient's preexisting clinical status. Proton-beam radiotherapy seems to be effective as an adjunct to surgery in achieving local tumor control. The timing of radiation therapy, however, remains controversial. Gamma knife surgery has been proposed as an adjunctive therapy, but the limited experience and short follow-up periods do not permit formulation of meaningful conclusions at this time. Recurrences are common, although in a subset of patients prolonged disease-free survival is demonstrated.

Chondroid chordoma: fine-needle aspiration cytology with histopathological, immunohistochemical, and ultrastructural study of two cases

Chondroid chordoma is a controversial and confusing entity that was originally described by Heffelfinger et al. (Cancer 1973; 32:410-420) as a biphasic malignant neoplasm possessing elements of both chordoma and cartilaginous tissue. Fine-needle aspiration (FNA) cytology of chondroid chordoma has not been described. The aim of our investigation was to characterize the chondroid area of chondroid chordoma and to compare the FNA features with those of well-differentiated chondrosarcoma. Clival and cervical spine chondroid chordomas were studied with light microscopy, immunohistochemistry, and electron microscopy. Chondroid chordomas demonstrated an epithelial nature by immunohistochemistry and ultrastructural studies. The FNA smears showed low cellularity, with loosely arranged or dispersed round cells in a myxoid background. Although the smears were similar to those of well-differentiated chondrosarcomas, they showed a positive reaction for epithelial markers. These findings reveal that chondroid chordoma is a variant of chordoma which possesses a hyaline matrix. Immunohistochemical demonstration of epithelial markers is useful to distinguish it from chondrosarcoma. Diagn. Cytopathol. 1999; 21:335-339.

Intracranial chondroid chordoma

Chordomas are rare tumours that arise from remnants of the primitive notochord. Chondroid chordoma is believed to be a variant of chordoma. We present a patient with a chondroid chordoma presenting with an oculomotor nerve palsy. Computed tomography (CT) demonstrated a mildly enhancing mass in the parasellar region and a markedly enhanced mass in the prepontine cistern. Magnetic resonance imaging also demonstrated a moderately enhanced, dumb-bell shaped mass. The parasellar mass was removed and the oculomotor nerve palsy disappeared three months after operation. Histology of the resected specimen revealed chondroid chordoma. One year after surgery she developed a left hemiparesis. CT demonstrated haemorrhage in the prepontine tumour. The encapsulated tumour with haematoma was removed and histology revealed that the tumour was composed of only chordoma tissue without cartilaginous tissue. The tumours located in the parasellar region and prepontine cistern enhanced differently on CT.

Chondroid chordoma versus low-grade chondrosarcoma of the base of the skull: can immunohistochemistry resolve the controversy?

The classification of cartilaginous tumors of the skull base, including chondroid chordoma and chondrosarcoma remains the subject of controversy. Critical review of the literature and our own experience of chordomas and cartilaginous tumors of the skull base led to the following conclusions: 1) Chondrosarcoma of the skull base is a distinct clinicopathological entity. The immunohistochemical staining pattern (cytokeratin negative, epithelial membrane antigen (EMA) negative) can be helpful in distinguishing it from chordoma with chondroid differentiation (cytokeratin positive, EMA positive). 2) The chondroid chordomas originally described by Heffelfinger et al. may have included some true chondrosarcomas with focal areas of myxoid chordomalike appearance. 3) Focal chondroid differentiation in chordoma is not such a rare phenomenon. Further study is needed to define whether chordoma with chondroid foci should be separated out from conventional chordoma as a distinct entity with a better prognosis.

Intracranial chordomas: a clinicopathological and prognostic study of 51 cases

Fifty-one patients with intracranial chordomas who were surgically treated between 1960 and 1984 were studied. Median patient age was 46 years, and 73% presented with diplopia or headache. Nineteen tumors were classified as the "chondroid" type. The extent of surgical removal was a biopsy in 11 patients and subtotal removal or greater in 40. Thirty-nine patients received postoperative radiation therapy. At the time of analysis, 17 patients were alive, and the estimated 5- and 10-year survival rates were 51% and 35%, respectively, for the group of 51 patients. Univariate analysis showed that: 1) patients undergoing resection lived longer (the 5-year survival rate was 36% for the 11 biopsy patients compared with 55% for the 40 patients who had resection; 2) patients who underwent postoperative radiotherapy tended to have longer disease-free survival times; and 3) overall and disease-free survival data were the same for patients with chondroid tumors and those with typical chordomas. Multivariate analysis showed that: 1) age was the factor most strongly associated with longer overall and disease-free survival; 2) diplopia was associated with longer survival; and 3) tumoral mitotic activity tended to be associated with shorter disease-free survival. One tumor metastasized to the cervical cord, and two tumors underwent anaplastic transformation. These data suggest that the prognosis in patients with chordomas is unfavorable, young age is the single factor most strongly associated with longer survival, surgical resection is beneficial, and postoperative radiotherapy may prolong disease-free survival.

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.

Chondroblastoma of bone. A clinical, radiological, light and immunohistochemical study

The clinical and morphological findings of 53 chondroblastomas in the files of the Bone Tumour Registry of Westphalia are presented. The mean age of all patients was 19.2 years. The male-to-female ratio was 1.5:1. Forty-two of the tumours (79.8%) were located in the long tubular bones and short tubular bones of the hands and were closely related to the growth plate. Six cases (11.3%) were found in the flat bones, 4 cases (7.5%) in the tarsal bones and 1 case (1.9%) in the craniofacial bones. The characteristic radiological feature of 44 investigated lesions was a mostly eccentric radiolucency with a geographic pattern of bone destruction and matrix calcifications. Periosteal reaction was evident in 9% of the cases. Most tumours demonstrate the typical morphological features of chondroblastoma, but 3 cases resembled a giant cell tumour. In 2 cases a haemangiopericytoma-like growth pattern was observed. Nine of the tumours had an aneurysmal bone cyst-like component. Vascular invasion was seen in 1 case. Immunohistochemically most cells in 30 of the cases and fetal chondroblasts in 3 cases were strongly positive with vimentin and S-100 protein. Collagen type II was positive in the chondroid matrix of the tumours and in fetal cartilage tissue; collagen type VI was present focally around individual tumour cells and was always seen in the chondroid matrix of the lesions and in fetal cartilage. These findings support the cartilaginous nature of these tumours. In paraffin sections, 46.6% of the cases revealed a distinct positive reaction of some tumour cells with the monoclonal cytokeratin antibody KL1 (molecular weight 55-57 kDa). Only 4 of them demonstrated a coexpression with the other monoclonal cytokeratin antibody CK (clone MNF 116, molecular weight 45-56.5 kDa). In paraffin sections all fetal chondroblasts were negative with both cytokeratin antibodies. Frozen sections of 3 tumours showed a strong positive reaction with both cytokeratin antibodies in many chondroblasts, indicating an "aberrant" cytokeratin expression. Osteoclast-like giant cells stained positive with leucocyte-common antigen (LCA) and with the macrophage-associated antibody KP1, but were negative with the other macrophage-associated antibody MAC 387. Recurrence rate was 10.7%. The clinical course of all tumours was benign.

Histogenesis of clear cell chondrosarcoma. An immunohistochemical study with osteonectin, a non-collagenous structure protein

The histogenesis of clear cell chondrosarcoma is still unclear: Apart from typical clear cell tumor areas, extensive production of woven bone formation suggests within the clear cell cartilagenous stroma is an intriguing phenomenon. Three cases of clear cell chondrosarcoma documented in the Bone Tumor Registry of Westphalia were examined for their patterns of osteonectin expression, and compared with other bone tumors of either osseous or cartilaginous origin, and with normal cartilage tissue. Found predominantly in osseous structures, the protein osteonectin takes part in the formation of new bone. The three clear cell chondrosarcomas showed a strong immunoexpression of osteonectin in clear cell, chondroid and in osseous tumor areas. Similarly, evidence of osteonectin was also found in osteoblastic and in chondroblastic osteosarcomas as well as in osteoblastomas. In contrast, osteonectin could not be demonstrated in the chondrosarcomas and mesenchymal chondrosarcomas from our registry that were analysed for comparison, and was found only minimally in the fibroblastic areas of dedifferentiated chondrosarcomas. The chondroblastic tumor components were always negative. There was no immunoexpression of osteonectin either in fetal or adult intervertebral disc tissue. The present immunohistochemical study of osteonectin has distinctly separated clear cell chondrosarcoma from the other variants of chondrosarcoma, and aptly verified the specificity of this entity. Moreover, the study would call for further histogenetic evaluation of clear cell chondrosarcoma, since the pattern of osteonectin expression in that tumor seems to indicate an osteogenic rather than a chondrogenic origin.

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.