Chordoid sarcoma (extraskeletal myxoid chondrosarcoma)

Clinicopathologic and radiologic features of extraskeletal myxoid chondrosarcoma: a retrospective study of 40 Chinese cases with literature review

The aim of this study is to describe the clinicopathologic and radiologic features of 40 cases of extraskeletal myxoid chondrosarcoma (EMC) from China. There were 25 males and 15 females (sex ratio, 1.7:1). Apart from an adolescent, all patients were adults with a median age of 49years. Twenty-four tumors (60%) occurred in the lower limb and limb girdles, especially the thigh, followed by the upper limb and limb girdles (20%) and trunk (10%). Other less commonly involved locations included the head and neck, sacrococcygeal region, and perineum. Tumors ranged in size from 1.5 to 19cm (mean, 7cm). By radiology, they appeared as hypoattenuated or isoattenuated masses on computed tomography with hyperintense signal on T2-weighted magnetic resonance imaging. Intralesional hypointense septa were present in most cases. Of the 40 tumors, 30 belonged to the classic subtype, whereas 9 cases were cellular, and 1 case had a rhabdoid phenotype. Tumor cells showed variable expression of synaptophysin (36%), S-100 protein (29%), epithelial membrane antigen (11%), and neuron-specific enolase (7%). Ki-67 index was remarkably higher in the cellular variant (mean, 30%). EWSR1-related rearrangement was detected in 12 of 14 cases tested by fluorescence in situ hybridization using break-apart probes. The overall 5- and 7-year survival was 71% and 60%, respectively. Awareness of the imaging features may help pathologists in the diagnosis of EMC. Fluorescence in situ hybridization also serves as a useful diagnostic tool for EMC, especially in the distinction from its mimics.

Extraskeletal myxoid chondrosarcoma: updated clinicopathological and molecular genetic characteristics

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft-tissue sarcoma characterized by distinctive morphological and cytogenetical features. As its name implies, EMC was believed to represent a variant of soft-tissue chondrosarcoma owing to its histological resemblance to chondroblastic tissue in the early stages of cartilage development or chondroid tumors such as skeletal chondrosarcoma. However, the chondroid nature has been a subject of controversy, and its line of differentiation remains to be determined. Consequently, the tumor is provisionally classified into a group of tumors of uncertain differentiation in the revised World Health Organization classification of tumors of soft tissue and bone. Moreover, immunohistochemical and ultrastructural features of neural or neuroendocrine differentiation have been recently reported in a subset of EMC, providing a new insight into their histogenetic nature. Chromosomal rearrangements involving 9q22, such as t(9;22)(q22;q12), and resultant NR4A3 fusion genes are tumor-type specific or pathognomotic for this entity and are assumed to play an important role in the development of EMC. Although the biological mechanisms and functions are largely unknown, the NR4A3-related pathway is considered a potential molecular target for future therapeutic intervention. Because of its protracted but resilient nature, a tenacious and long-term follow up is necessary for any patient.

Pathologic and molecular aspects of soft tissue sarcomas

This article retains the conventional approach to the classification of soft tissue sarcomas, dividing them into several major histogenetic categories based on their overall microscopic appearance, tissue differentiation pattern, and biologic potential. The author advocates a multimodal approach, in which four distinctive data sets--clinical, radiographic, microscopic, and, in some cases, molecular--are considered to establish the diagnosis and treatment plan. Such step-wise analysis is more likely to lead to consistency and accuracy as compared with an intuitive approach based on fragmentary data. The author describes individual lesions of soft tissue as clinicopathologic entities and believes that they can be more accurately diagnosed and appropriately treated with the help of data generated by a multidisciplinary team. In addition, this article emphasizes the need to use emerging molecular techniques that can provide important clues for both diagnosis and prognosis.

Extraskeletal myxoid chondrosarcoma: a Multi-Institutional Study of 42 Cases in Japan

BACKGROUND

Extraskeletal myxoid chondrosarcoma (EMC) is a rare malignant neoplasm. Despite a consensus for the distinct clinicopathologic entity of EMC, its clinical features remain controversial. In addition, most studies have contained a small number of patients who underwent definitive surgical treatment.

METHODS

Forty-two cases of EMC, which had been identified from files of eight affiliated hospitals and confirmed for histologic diagnosis at the Pathology Center, were analyzed for histologic grade, demographics, treatments, outcomes, and prognostic factors. The average follow-up period was 7.4 years.

RESULTS

Included in the study were 20 men and 22 women with a mean age at diagnosis of 52.1 years. The tumors were located mainly in the lower extremities (69%). Thirty-three tumors (79%) were classified as Grade 1 and nine as Grade 2 according to the modified French System. Overall survival was 100% at 5 years and 88% at 10 years. Disease-free survival was 45% at 5 years and 36% at 10 years. Inadequate initial surgery was defined as a significant risk factor for local recurrence by univariate analysis of all 42 patients but not by the analysis of those 30 patients who had undergone wide tumor excision or amputation. Wide excision led to the recurrence rate of 14%.

CONCLUSIONS

These findings supported the role of wide excision in the local control of EMC, irrespective of the previous excision procedure or recurrence. The protracted clinical course of the tumors and the presence of patients who had distant metastasis develop after definitive surgery of the primary tumor represented EMC as intermediate malignancy.

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.

Extraskeletal myxoid chondrosarcoma: a clinicopathologic, immunohistochemical, and molecular analysis of 18 cases

Extraskeletal myxoid chondrosarcoma (EMCS) is an uncommon clinicopathologically well-defined tumor, but its pathogenesis and biologic behavior are poorly understood. We reviewed 18 cases of EMCS to verify clinicopathologic features and immunohistochemical profiles together with molecular detection of the tumor-specific fusion genes. The tumors were located mainly in the proximal extremities and limb girdles (72%). Two tumors arose at unusual anatomic sites: the finger and the hip joint. Nine of the 17 followed-up patients were alive and disease free, 4 were alive with recurrences and/or metastases, and 4 died of the tumor. Fifteen tumors showed typical features of EMCS, and 3 had hypercellular areas in addition to conventional EMCS areas. The tumors were variably immunoreactive for S-100 protein (50%), NSE (89%), peripherin (60%), and synaptophysin (22%). Chromogranin A and some epithelial markers (AE1/AE3, CAM5.2, and epithelial membrane antigen) were entirely negative. Frequent expressions of the neural/neuroendocrine markers suggest possible neural/neuroendocrine differentiation in at least some EMCSs, in addition to chondroid differentiation. In a reverse-transcription polymerase chain reaction (RT-PCR) assay using paraffin-embedded specimens, EWS-CHN or TAF2N-CHN fusion gene transcripts characteristic of EMCS could be detected in 15 (83%) of the 18 cases: EWS-CHN type 1 in 11 cases, EWS-CHN type 2 in 1, and TAF2N-CHN in 3. Three fusion-negative cases included 2 conventional EMCSs and 1 considered a "cellular" variant of the tumor. None of 30 other soft tissue and bone tumors with myxoid or chondroid morphology that we examined contained these fusion genes. Thus, RT-PCR detection of EWS-CHN or TAF2N-CHN fusion gene using archival paraffin-embedded tissue is a feasible and useful ancillary technique for the diagnosis of EMCS.

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.

Myxoid chondrosarcoma of the sphenoid sinus and chondromyxoid fibroma of the iliac bone: cytomorphologic findings of two distinct and uncommon myxoid lesions

Myxoid chondrosarcoma (MCS) and chondromyxoid fibroma (CMF) are two uncommon myxoid cartilaginous neoplasms with distinct cytologic features, histologic patterns, and immunoprofiles. Because these neoplasms have characteristic biological behaviors and management, their correct diagnosis is crucial to avoid debilitating and unnecessary surgical procedures. We report the imprint cytology (IC) preparation findings along with the differential diagnosis in one case each of myxoid chondrosarcoma and chondromyxoid fibroma of the splenoid sinus and iliac bone, respectively. The two great mimickers for these neoplasms, chordoma and chondrosarcoma, represent difficult diagnostic challenges, especially when MCS and CMF occur in unusual locations. IC in conjunction with the clinical and radiologic findings can provide a rapid preliminary intraoperative diagnostic interpretation which can aid in planning the immediate surgical management, as well as guide specific tissue triage for key ancillary studies such as electron microscopy and cytogenetic analyses. To the best of our knowledge, there have been no cytologic reports of MCS of the sphenoid sinus and CMF of the iliac bone.

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.

Extraskeletal myxoid chondrosarcoma: a reappraisal of its morphologic spectrum and prognostic factors based on 117 cases

Extraskeletal myxoid chondrosarcoma (EMC), a phenotypically and genotypically distinctive entity, has generally been viewed as a low-grade sarcoma. No studies regarding clinical and morphologic prognostic factors have been performed on a large series of cases with long-term follow-up because of the rarity and protracted clinical course of EMC. The clinical, morphologic, and immunohistochemical features of 117 previously unreported cases were studied and statistically analyzed. The male-to-female ratio was 2:1. The median patient age was 52 years (range, 6-89 years), and the median tumor size was 7 cm (range, 1.1-25 cm). All tumors occurred within the deep subcutis or deeper soft tissues, with 80% occurring in the proximal extremities or limb girdles and 20% in the trunk. Most initial tumor excisions were intralesional or marginal. Follow-up information was available in 99 cases (median, 9 years: range, 2 months-22 years). Forty-eight patients were disease-free, and 41 patients had evidence of disease (18 of these had died of disease). Ten additional patients survived, but their disease status was unknown. There were local recurrences in 40 (48%) of 83 patients, 23 (58%) of whom had multiple local recurrences. Metastases occurred in 35 (46%) of 76 patients. The estimated 5-, 10-, and 15-year survival rates were 90%, 70%, and 60%, respectively. All cases had histologic features characteristic of classical EMC, at least focally. Cellular foci devoid of myxoid matrix and reminiscent of chondroblastoma, Ewing's sarcoma, monophasic and poorly differentiated synovial sarcoma, fibrosarcoma, and rhabdoid tumor were identified in 29% cases. Older patient age, larger tumor size, and tumor location in the proximal extremity or limb girdle were adverse prognostic factors identified by multivariate analysis. Metastasis also adversely affected survival, although local recurrence did not. This study shows that EMC has a unique clinical course, including a high rate of local recurrence, prolonged survival after metastasis in some cases, and eventually a high rate of death due to tumor. These features distinguish EMC from low-grade sarcomas. This study shows that histologic grading is of no prognostic value in EMC because prognosis is dictated primarily by certain clinical features. Histologic recognition of classical EMC and cellular and solid, nonmyxoid variants is important, however, in view of EMC's distinctive biologic behavior.

Skeletal and extraskeletal myxoid chondrosarcoma: a comparative clinicopathologic, ultrastructural, and molecular study

BACKGROUND

Skeletal myxoid chondrosarcoma (SMC) is considered to be either a typical chondrosarcoma with prominent myxoid alterations or an altogether unique malignant cartilage tumor. Extraskeletal myxoid chondrosarcoma (EMC) is a relatively rare but well-recognized neoplasm. It was initially thought to be a low grade sarcoma of cartilage derivation and was recently found, in most cases, to contain a reciprocal t(9;22), resulting in a fusion of the EWS and CHN genes. Are SMC and EMC the same entity arising in two different locations, or are they two separate entities? To the authors' knowledge, this study represents the first systematic attempt to answer this question.

METHODS

Forty consecutive cases of EMC (20 cases) and SMC (20 cases) were compared by light and electron microscopy, immunohistochemistry, and molecular analysis. The mean clinical follow-up for both groups was 55 months. Histologic criteria for SMC consisted of 95% myxoid matrix, with only minimal hyaline cartilage formation.

RESULTS

The gender distribution was identical in both groups (13 males and 7 females). The mean age was 55 years for EMC patients and 45 years for SMC patients. The EMC tumors were predominantly located in the deep soft tissues of the lower extremity (60%) and buttock (20%), and the mean tumor size was 13 cm. SMC was most commonly located in the bones around the hip joint (pelvis 35%; proximal femur 20%) and shoulder (20%); the mean size was 9 cm. Histologic grade in the EMC group correlated with survival (82% of the high grade tumors metastasized). Electron microscopy performed in 8 EMC cases revealed intracisternal microtubules in 3 cases and prominent mitochondria in 5, whereas in 5 SMC cases it revealed only inconspicuous organelles. Molecular analysis for the EWS-CHN fusion RNA resulting from the t(9;22) was performed in 15 cases (9 EMC and 6 SMC) and was detected in 7 of 9 EMC cases and 0 of 6 SMC cases. In one case, the molecular structure of the EWS-CHN fusion RNA was novel. The probability of metastasis was significantly higher (P=0.004) for the EMC group than for the SMC group.

CONCLUSIONS

Although similar light microscopic features are noted in EMC and SMC, fundamental differences are noted at the ultrastructural and molecular levels, suggesting that EMC and SMC represent two distinct entities in the chondrosarcoma family of tumors.

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 clinicopathologic and immunohistochemical study of four cases of an unusual soft tissue neoplasm

Four soft tissue tumors corresponding with the previously reported parachordoma are described. Three of the patients were men, and one was a woman, and their ages ranged from 14 to 53 years (mean age, 29). The tumors were located either superficially or within muscle, and, in one case, involved a tendon. Histologically, the tumors displayed whorls, nests, and pseudoglandular cords of uniform polygonal cells with eosinophilic, vacuolated cytoplasm, in a focally myxoid stroma. Transitions were seen between fascicles of ovoid-spindled cells, with scanty cytoplasm in a fibrous stroma, and, in one case, whorls of bland spindly cells were also present. Electron microscopy of one case showed cells with short interdigitating microvilli and ill-defined junctions. The principal cells in all cases were positive for S100 protein, Leu-7, keratin (CAM5.2), and epithelial membrane antigen (EMA). All tumors were negative with antibody AE1 and with antibodies to cytokeratins CK7 and CK19. No tumor displayed immunoreactivity for carcinoembryonic antigen (CEA), muscle specific actin (MSA), smooth muscle actin (SMA), desmin, glial fibrillary acid protein (GFAP), CD31, or CD34. Parachordoma appears to be an entity with clinical and pathological differences from chordoma, which has a different cytokeratin profile, behaves in a more aggressive fashion, and can dedifferentiate. The differential diagnosis includes myxoid chondrosarcoma, myoepithelial cell tumor, ossifying fibromyxoid tumor, and chondroid lipoma.

Myxoid chondrosarcoma (chordoid sarcoma) of bone: a report of two cases and review of the literature

BACKGROUND

Chondrosarcoma of bone is a well recognized, relatively common clinicopathologic entity. Morphologically distinct soft tissue chordoid sarcoma (CS), or extraskeletal myxoid chondrosarcoma, is a relatively rare tumor that has generally been documented in extraosseous soft tissues.

METHODS

The clinical and pathologic features of two patients with biopsy-proven CS from the pathology files of the Mayo Clinic and St. Thomas's Hospital were evaluated. Routine hematoxylin and eosin-stained slides were reviewed in both cases. Sections from both were examined immunohistochemically using the avidin-biotin-peroxidase technique and employing commercially available antibodies to the following antigens: S-100 protein, cytokeratin (AE1/AE3), epithelial membrane antigen (EMA), CD31, and factor VIII. Appropriate positive and negative controls were utilized throughout these procedures. Cytogenetic analysis was performed on fresh samples obtained from one tumor. Clinical data were obtained from the patients' medical records.

RESULTS

The two cases of primary CS of bone arose from the right distal femur and right scapula, respectively, in 2 men ages 48 and 76 years, respectively. Morphologically, the tumors were lobulated, multinodular, and comprised of a uniform population of rounded to slightly spindled cells. Nuclei were hyperchromatic with inconspicuous nucleoli and surrounded by clear, vacuolated to eosinophilic cytoplasm. Neoplastic cells were arranged in anastomosing chords, strands, and, less often, nests and pseudopapillary structures embedded in an abundant, mostly hypovascular, mucinous matrix. Foci of hemorrhage and cystic degeneration were present in both tumors. No well developed hyaline cartilage or neoplastic osteoid was observed. Immunohistochemically, one neoplasm showed focal positivity for S-100 protein but was uniformly negative for cytokeratin (AE1/AE3), factor VIII, and CD31. The other tumor showed no immunopositivity with cytokeratin, EMA, or S-100 protein. Cytogenetic analysis in the latter tumor revealed a nonrandom reciprocal chromosomal translocation, t(9;22)(q22-31;q11-12). Both patients developed local recurrences and widespread distant metastases. Wide surgical excision was the primary mode of therapy. One patient died of tumor.

CONCLUSIONS

Skeletal CS is an extraordinarily rare neoplasm with a distinct morphology. Although follow-up data were limited to only four examples, including two from the literature, the clinical course appears worse than that for usual chondrosarcoma of bone. Wide surgical resection appears to represent the best mode of therapy. The role of chemotherapy and radiation therapy has not been clearly defined.

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.

Myxoid chondrosarcoma of soft tissue and bone: a retrospective study of 11 cases

This article describes 11 cases of myxoid chondrosarcoma (MCS), with 10 arising in soft tissues and one developing in bone. Most of the tumors (six) were located in the lower extremities. Two lesions developed in the fingers, a previously unreported location for MCS. Four cases showed secondary bone destruction, which is a rare feature of this tumor. S100 protein was expressed by tumor cells in all the specimens. Four out of eight tumors studied by electron microscopy contained intracisternal microtubular structures. Two tumors showed areas of spindle cell proliferation that merged with the areas of typical myxoid pattern. The cells in these areas had fibroblastic/myofibroblastic features by electron microscopy and were found to express cytokeratin by immunohistochemistry. The concomitant expression of cytokeratin and S100 protein in the spindle cells suggests that they represent a less differentiated cartilaginous component with unusual features. The clinical significance of the presence of such spindle cell areas presently remains unknown. Although myxoid chondrosarcoma is a slow-growing tumor, it has a high potential for metastases. Four of 11 patients in this series developed metastases.

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.

Translocation (9;22)(q22;q12). A recurrent chromosome abnormality in extraskeletal myxoid chondrosarcoma

Cytogenetic analysis of a case of extraskeletal myxoid chondrosarcoma revealed a reciprocal translocation between 9q and 22q in almost all metaphases analyzed. Structural rearrangements involving 9q and 22q have been reported previously in three cases of extraskeletal myxoid chondrosarcoma. The breakpoints on chromosomes 9 and 22 in the present case were in regions 9q22-q31 and 22q11-q12.2, respectively. The same breakpoints were present in all three previously reported cases. Thus, this recently identified rearrangement of 9q and 22q may serve as a critical cytogenetic parameter for the diagnosis and classification of extraskeletal myxoid chondrosarcoma, as well as being a primary chromosomal event in the course of development of this rare malignancy.

Case report 829: Intramuscular myxoid chondrosarcoma

A 61-year-old man presented with a 6-month history of a painless mass in the right buttock. Although the MR appearance of myxoid neoplasms is variable, a myxoid neoplasm was suspected on the basis of the MR study. Percutaneous needle biopsy results yielded a diagnosis of intramuscular myxoma. Myxoid chondrosarcoma, however, was diagnosed at the time of excisional biopsy. One should be wary of a diagnosis of intramuscular myxoma based solely on the results of percutaneous needle biopsy. In addition, myxoid chondrosarcoma of the soft tissues can have a variable appearance on T1-weighted imaging.

Extraskeletal myxoid chondrosarcoma with intracisternal microtubules

A case of extraskeletal myxoid chondrosarcoma with intracisternal microtubules is presented. The microtubules were generally straight, parallel, closely packed, and evenly spaced, but they did not form geometric arrays. Aggregates of stromalike myxoid material were present in the cisternae and the adjacent cytoplasm. Microtubules were never found within the cytoplasm. A similar ultrastructural appearance was seen in 4 of 10 other examples of extraskeletal myxoid chondrosarcoma.

Intracranial extraskeletal myxoid chondrosarcoma with special reference to lamellar inclusions in the rough endoplasmic reticulum

An extraskeletal myxoid chondrosarcoma in the pineal region was studied by light and electron microscopy. The immunohistochemical positivity for S-100 protein, vimentin and collagen type II favored a chondrocytic origin of the tumor. In addition to the well-described ultrastructural features suggestive of a cartilagenous nature, this tumor had unusual lamellar inclusions in the rough endoplasmic reticulum. To the best of our knowledge, this is the first report of these special inclusion bodies in a myxoid chondrosarcoma.

Parachordoma: an ultrastructural and immunohistochemical study

A case of parachordoma of the left calf in a 19-year-old Chinese female is reported. The tumour showed multinodular growth pattern and consisted of round or oval tumour cells with abundant eosinophilic cytoplasm and myxoid matrix. Tumour cells formed small nests and sometimes showed concentric arrangement. Physaliferous-like cells and undifferentiated spindle cells were occasionally observed among the cell nests. The myxoid matrix was positive for high-iron diamine stain, indicating the presence of chondroitin 4- and 6-sulphates and keratan sulphate. Ultrastructurally, well-developed rough endoplasmic reticulum, abundant intermediate filaments, microvillous cytoplasmic processes, pinocytic vesicles, and desmosome-like junctional structures were found. Tumour cells were positive for S-100 protein and vimentin, but negative for cytokeratin, epithelial membrane antigen, carcinoembryonic antigen, and desmin. These results are consistent with the definition of parachordoma as a soft tissue neoplasm consisting of cells with histology and ultrastructure similar to those of chordoma cells but with immunohistochemistry similar to that of chondroid tumour cells.

Extraskeletal myxoid chondrosarcoma. A clinicopathologic study of ten patients with long-term follow-up

Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma that has been reported to have a relatively good prognosis. The authors report ten patients with EMC on whom there was a minimum follow-up of 10 years. The patients' ages ranged from 31 to 72 years (mean, 57 years); there were six men and four women (seven white, three black). The tumor locations included the knee area and thigh (three patients each), the shoulder (two patients), and the leg and foot (one patient each). The tumors ranged from 3.5 to 18 cm in greatest dimension (median, 11.5 cm). All cases had typical histologic features. Lung metastases developed in all patients but one, and three patients had extrathoracic metastases (one in regional lymph nodes; one in subcutis; and one widespread). Four of the patients who had metastases also had local recurrence, as did the only patient without known metastases. Seven patients died of tumor at 4, 5, 8, 10, 15, 16, and 17 years, respectively, and the three remaining patients were alive with metastatic disease at latest follow-up of 13, 14, and 16 years. The authors' results are distinctly different from those previously reported in series with shorter follow-up times. The authors conclude that extraskeletal myxoid chondrosarcomas are indolent but resilient and capricious tumors with a high potential for metastasis, especially to the lungs, over the long-term.

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.

Unusual extraskeletal myxoid chondrosarcoma

We describe an unusual soft tissue tumor occurring within the rectus femoris muscle of a 64-year-old woman. The site, size, macroscopic, and histological appearances were all consistent with an extraskeletal myxoid chondrosarcoma. However, the present case differs significantly from previous reports of this uncommon tumor in that electron microscopy did not show any evidence of chondroblastic differentiation. Furthermore, the cells failed to stain for vimentin while labeling intensely for neuron-specific enolase, contained large numbers of cytolysosomes having a multivesicular appearance, and focally produced an external lamina. Based on the typical histological appearances we conclude that this is an unusual variant of extraskeletal myxoid chondrosarcoma in which there is evidence of nerve sheath differentiation.

Cellular variant of extraskeletal myxoid chondrosarcoma of abdominal wall--a case report with comparative immunohistochemical study on cartilaginous collagenous proteins in various myxoid mesenchymal tumors

A rare cellular variant of recurrent extraskeletal myxoid chondrosarcoma occurring in the right lower abdominal wall of a 70-year-old man, is presented with emphasis on a characteristic distribution pattern of cartilaginous collagen proteins in the stroma. While the primary and the first recurrent tumors showed the typical histology of extraskeletal myxoid chondrosarcoma, the later tumor, which recurred 14 years after the first resection, comprised mostly compact nodules of proliferating anaplastic cells with little mucoid stroma. Some areas presented a hemangiopericytomatous pattern. A few nodules possessed abundant myxoid stroma. Immunohistochemically, type II collagen was demonstrated in the stroma of some cellular areas, and type VI collagen was intensely stained around individual tumor cells both in cellular and myxoid areas. In a comparative immunohistochemical study, the same distribution pattern of cartilaginous collagen proteins was observed only in skeletal myxoid chondrosarcomas, but not in other mesenchymal tumors with abundant myxoid stroma. These findings seem to support the cartilaginous nature of extraskeletal myxoid chondrosarcoma, and will facilitate the differential diagnosis of soft-tissue tumors with myxoid stroma.

Chromosomal abnormality t(9;22)(q22;q12) in an extraskeletal myxoid chondrosarcoma characterized by fine needle aspiration cytology, electron microscopy, immunohistochemistry and DNA flow cytometry

A multidisciplinary approach was taken to characterize a soft tissue tumour. In smears prepared from aspirated material, uniform tumour cells, embedded in a myxoid matrix and partly arranged in a lace-like pattern, were found. Histopathology showed a lace-like pattern of cells in a matrix of hyaluronidase-stable mucins. Cytoplasmic positivity for S-100 protein was found in some tumour cells. Electron microscopic analysis revealed intracisternal aggregates of microtubules. All these features are consistent with the diagnosis of extraskeletal myxoid chondrosarcoma (EMC). DNA flow cytometry showed a diploid DNA content. Cytogenetic examination revealed the tumour karyotype 45,XY,t(2;11)(q31;p15),t(9;22)(q22.3;q12),dic(13;22)(p11;p13). Because similar 9;22-translocations have been described in two other cases of EMC, we conclude that t(9;22)(q22-31;q11-12) is a specific rearrangement in this tumour type. Cytogenetic analysis may thus be of diagnostic value in the examination of tumours with this and similar histologies.

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.

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.

Chondroid chordoma

We reject the notion that the concept of "chondroid chordoma" be abandoned in favor of an interpretation of the cartilaginous origin of these lesions. We have demonstrated by electron microscopic and immunohistochemical means that these neoplasms can exhibit distinctly epithelial characteristics in their chondroid as well as their epithelial areas. The presence of desmosomes, cytokeratin, carcinoembryonic, and epithelial membrane antigen in the cells of the chondroid as well as the epithelial areas; the presence of the microtubular inclusions, vimentin, and S-100 protein in the cells of the epithelial as well as chondroid areas; and the intermingling of the two and gradual transitions from one to the other all point to the conclusion that the chondroid and epithelial areas are only differing morphologic expressions of the same entity. The gradual evolution witnessed in the sequential biopsies of this case study, through which a predominantly chondromatous neoplasm became a chordoma of typical histologic appearance, provides further strong evidence to support the contention that chondroid chordoma is a variant of chordoma and not a primary chondrocytic neoplasm.

Straight intracisternal tubules in rough endoplasmic reticulum of human melanoma cells

This case presentation illustrates peculiar tubular aggregates in rough endoplasmic reticulum (RER) of human melanoma cells, a location in which they have been reported in a small percentage of malignant melanomas.

Microtubular aggregates within rough endoplasmic reticulum: an unusual ultrastructural feature of extraskeletal myxoid chondrosarcoma

Two extraskeletal myxoid chondrosarcomas were examined by electron microscopy. In addition to the well-described ultrastructural features indicative of chondroblastic origin, both of these chondrosarcomas had unusual parallel microtubules packed within rough endoplasmic reticulum. This paper reviews the differential diagnosis of extraskeletal myxoid chondrosarcoma and discusses ultrastructural examination as a valuable adjunct in the diagnosis of this uncommon soft tissue tumor.

Gastric leiomyosarcoma with massive myxoid degeneration. A histochemical and ultrastructural study

Histochemical and ultrastructural features of a gastric myxoid leiomyosarcoma from a 55-year-old man were examined. At autopsy, the tumor was located mainly in the greater omentum and was directly connected to a coinsized gastric tumor. Multiple hepatic metastases and peritoneal disseminations were noted. Light-microscopically, the tumor was composed of a prominent myxoid stroma and ovoid or rounded tumor cells. The myxoid stroma was stained weakly basophilic with hematoxylin and eosin, and was mainly composed of hyaluronic acid. Tumor cells in the stomach were spindle-shaped and apparently myogenic. Ultrastructurally, the gastric tumor cells showed a loose cohesion with junctional apparatuses, pinocytotic vesicles, basal laminae, and cytoplasmic filaments with focal densities. Tumor cells in the omentum and the liver, however, were poorly differentiated and showed an epithelioid nature in part. This unique leiomyosarcoma is reported with some differential diagnoses from other myxoid sarcomas.

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.

Myxoid chondrosarcoma with a translocation involving chromosomes 9 and 22

Myxoid chondrosarcoma is an uncommon neoplasm thought to be derived from mesenchymal chondrocytic cells. Although cytogenetic abnormalities have been reported in sarcomas, too few cases have been studied to determine the frequency of nonrandom chromosomal changes in mesenchymal tumors. In this article, we describe a chondrosarcoma with a nonrandom reciprocal translocation t(9;22)(q22;q11). The cellular homologue to the retrovirus transforming gene of simian sarcoma virus is located on chromosome #22, and its possible significance in this case is discussed.