Ultrastructural study of conventional chondrosarcomas and myxoid- and mesenchymal-chondrosarcomas

Mesenchymal chondrosarcomas showing immunohistochemical evidence of rhabdomyoblastic differentiation: a potential diagnostic pitfall

The diagnosis of mesenchymal chondrosarcoma, a distinctive biphasic malignant neoplasm harboring the HEY1-NCOA2 gene fusion and consisting of primitive round to spindled cells admixed with foci of relatively mature hyaline cartilage, is usually straightforward by morphologic evaluation alone. However, in the setting of a limited biopsy, specimens lacking cartilage generate a broad differential diagnosis, encompassing a variety of other primitive sarcomas, including spindle cell/sclerosing rhabdomyosarcoma. Although a small number of cases of mesenchymal chondrosarcoma with aberrant skeletal muscle marker expression have been reported, pathologists are largely unaware of this potential diagnostic pitfall. We report 6 additional cases of mesenchymal chondrosarcoma showing expression of multiple skeletal muscle markers, including one case initially misdiagnosed as "spindle cell/sclerosing rhabdomyosarcoma" on needle biopsy. Awareness of this phenomenon and judicious application of molecular diagnostic testing for the HEY1-NCOA2 fusion are critical to avoid misclassification of mesenchymal chondrosarcoma as rhabdomyosarcoma, with potentially adverse patient impact.

Primary extraskeletal myxoid chondrosarcoma of bone: Report of three cases and review of the literature

Extraskeletal myxoid chondrosarcoma is a rare neoplasm of soft tissue. The usual location is in deep parts of the proximal extremities and limb girdles in middle-aged adults. The bone location as primary location is extremely rare and few cases are reported. We present three cases arising in bone with molecular confirmation using both RT-PCR and FISH analysis. Patients include two men and one woman with an age of 62, 69 and 73 years old. The mean size of the lesion was 13cm (range 8-18cm). Tumors arose in the iliac bone in two cases and in the proximal humerus in the other case. At time of diagnosis the three cases show bone cortex and soft tissue involvement. On imaging, lesions have a lobular pattern, are purely lytic, but take up contrast medium after injection. Two patients are alive with disease (local recurrence and lung metastasis) after five years and five years and six months, respectively and one patient died of disease two years after the diagnosis. The primary extraskeletal myxoid chondrosarcoma of bone seems to have a more aggressive behavior than the soft tissue counterpart. The molecular confirmation of diagnosis using RT-PCR is necessary to do the differential diagnosis with other entities, in particular with myoepithelioma that shows similar morphological features and EWSR1 and FUS genes rearrangement.

Utility of transmission electron microscopy in small round cell tumors

Small round cell tumors (SRCTs) are a heterogeneous group of neoplasms composed of small, primitive, and undifferentiated cells sharing similar histology under light microscopy. SRCTs include Ewing sarcoma/peripheral neuroectodermal tumor family tumors, neuroblastoma, desmoplastic SRCT, rhabdomyosarcoma, poorly differentiated round cell synovial sarcoma, mesenchymal chondrosarcoma, small cell osteosarcoma, small cell malignant peripheral nerve sheath tumor, and small cell schwannoma. Non-Hodgkin's malignant lymphoma, myeloid sarcoma, malignant melanoma, and gastrointestinal stromal tumor may also present as SRCT. The current shift towards immunohistochemistry and cytogenetic molecular techniques for SRCT may be inappropriate because of antigenic overlapping or inconclusive molecular results due to the lack of differentiation of primitive cells and unavailable genetic service or limited moleculocytogenetic experience. Although usage has declined, electron microscopy (EM) remains very useful and shows salient features for the diagnosis of SRCTs. Although EM is not always required, it provides reliability and validity in the diagnosis of SRCT. Here, the ultrastructural characteristics of SRCTs are reviewed and we suggest that EM would be utilized as one of the reliable modalities for the diagnosis of undifferentiated and poorly differentiated SRCTs.

Chondrosarcoma with myxoid change: a study using a quick-freezing and deep-etching method

A middle-aged Japanese woman visited the Orthopedics Department of Nihon University Nerima Hikarigaoka Hospital complaining of pain in the left hip joint that had started approximately 8 months earlier. Following several examinations, including imaging diagnoses, an incisional biopsy demonstrated a malignant acetabular bone tumor, which was removed and examined by a quick-freezing and deep-etching (QF-DE) method, conventional electron microscopy, and light microscopy. Histologically, the tumor was a chondrosarcoma with marked myxoid changes. An interesting extracellular matrix was observed by the QF-DE method. The myxoid area consisted of a fine meshwork of proteoglycans (PG) without obvious aggrecans, which resembled that of PG usually present in the pericellular matrix of normal cartilage. Thin collagen fibrils with pleated surface structures of regular periodicity were also seen, which were sparsely distributed in wide areas except for the pericellular matrix. These collagen fibrils were of the type that are mainly located in the pericellular side of the territorial matrix in normal cartilage. A myxoid matrix consisting of thin collagen fibrils on the background of pericellular type PG suggested that the myxoid matrix in the chondrosarcoma resembled those of the pericellular and pericellular sides of the territorial matrices in normal cartilage.

From the archives of the AFIP: imaging of primary chondrosarcoma: radiologic-pathologic correlation

Chondrosarcoma is a malignant tumor that produces cartilage matrix, and lesions that arise de novo are called primary. Primary chondrosarcoma is the third most common primary malignant tumor of bone, constituting 20%-27% of all primary malignant osseous neoplasms. There are numerous types of primary chondrosarcomas, including conventional intramedullary, clear cell, juxtacortical, myxoid, mesenchymal, extraskeletal, and dedifferentiated. The conventional intramedullary chondrosarcoma is the most frequent type, and it most commonly involves the long bones or pelvis in up to 65% of cases. Although the pathologic appearance varies with specific lesion type, chondrosarcomas grow with lobular type architecture, and these hyaline cartilage nodules demonstrate high water content and peripheral enchondral ossification. Imaging features directly reflect this pathologic appearance, and the various subtypes often show distinctive features. Radiographic findings often suggest the diagnosis of chondrosarcoma because of identification of typical "ring-and-arc" chondroid matrix mineralization (representing the enchondral ossification) and aggressive features of deep endosteal scalloping and soft-tissue extension. These latter features are usually best assessed, as is lesion staging, with computed tomography (CT) or magnetic resonance (MR) imaging. CT is optimal to detect the matrix mineralization, particularly when it is subtle or when the lesion is located in anatomically complex areas. Both CT and MR imaging depict the high water content of these lesions as low attenuation and very high signal intensity with T2-weighting, respectively. Understanding and recognizing the spectrum of appearances of the various types of primary chondrosarcoma allow improved patient assessment and are vital for optimal clinical management including diagnosis, biopsy, staging, treatment, and prognosis.

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.

Cell differentiation and matrix gene expression in mesenchymal chondrosarcomas

Mesenchymal chondrosarcomas are small-cell malignancies named as chondrosarcomas due to the focal appearance of cartilage islands. In this study, the use of in situ detection techniques on a large series of mesenchymal chondrosarcoma specimens allowed the identification of tumor-cell differentiation pathways in these neoplasms. We were able to trace all steps of chondrogenesis within mesenchymal chondrosarcoma by using characteristic marker genes of chondrocytic development. Starting from undifferentiated cells, which were negative for vimentin and any other mesenchymal marker, a substantial portion of the cellular (undifferentiated) tumor areas showed a chondroprogenitor phenotype with an onset of expression of vimentin and collagen type IIA. Cells in the chondroid areas showed the full expression panel of mature chondrocytes including type X collagen indicating focal hypertrophic differentiation of the neoplastic chondrocytes. Finally, evidence was found for transdifferentiation of the neoplastic chondrocytes to osteoblast-like cells in areas of neoplastic bone formation. These results establish mesenchymal chondrosarcoma as the very neoplasm of differentiating premesenchymal chondroprogenitor cells. The potential of neoplastic bone formation in mesenchymal chondrosarcoma introduces a new concept of neoplastic (chondrocytic) osteogenesis in musculoskeletal malignant neoplasms, which qualifies the old dogma that neoplastic bone/osteoid formation automatically implies the diagnosis of osteosarcoma.

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.

Mesenchymal chondrosarcoma of the foot, an unusual location: case report and review of the literature

We present a case of primary mesenchymal chondrosarcoma of the proximal phalanx of the first toe. The bones of the foot represent an infrequent primary site for this neoplasm. The tumour consisted of layers of undifferentiated round cells with scanty cytoplasm and hyperchromatic nuclei. The presence of brain, lung, and left auricle metastasis was demonstrated, and the patient died due to brain edema 18 days after admission. Mesenchymal chondrosarcoma is a rare tumor that more frequently involves the pelvic bones, the femur, and the humerus. To our knowledge, only nine cases of primary mesenchymal chondrosarcoma arising from the bones of the foot have been previously reported, with none involving the phalanx of the toe.

Mesenchymal chondrosarcoma. A cytogenetic, immunohistochemical and ultrastructural study

A case of mesenchymal chondrosarcoma was studied. The tumor was near-tetraploid and the clonal structural chromosomal abnormalities included add(7)(p13), add(22)(q13), markers, and double minutes. The ultrastructural and immunohistochemical findings were consistent with the diagnosis. Strong immunoreactivity for desmin was an unusual, not previously reported, feature of the neoplasm.

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.

Mesenchymal chondrosarcoma of the jaw--report of a case and review of 41 cases in the literature

A case of mesenchymal chondrosarcoma in the mandible of a 35-year-old woman is presented. In a thorough survey of the world literature, 41 cases of mesenchymal chondrosarcoma occurring the jaw are reviewed.

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.

Ossifying fibromyxoid tumor of soft parts

A histologically uncommon soft-tissue tumor of the extremities and neck of a 54-year-old male is reported. The solid, bony-hard tumors occurred at the inner region of the right thigh at 44 years of age with additional tumor formation at the posterior region of the same thigh, at the inner region of the right upper arm and at the neck during the following 10 years. All tumors were located in the deep muscle layer. The neck tumor directly invaded the fifth cervical vertebra and later the upper mediastinum. Histologically, all three tumors of the extremities contained mixed lobular growths of round-to-fusiform cells with myxoid matrix and an extensive bone formation. The tumor cells showed a small round nucleus and eosinophilic cytoplasm lacking cytoplasmic glycogen. The myxoid matrix was stained significantly by alcian blue and colloidal iron and was digested completely by pretreatment with hyaluronidase. Another major component was mature bone trabeculae showing a dense meshwork throughout the entire tumor with active bone formation toward the periphery. Positive immunostaining was obtained against antivimentin and S-100 protein antibodies. We suggest that this uncommon tumor can be tentatively distinguished as an ossifying fibromyxoid tumor of soft parts, (an entity defined by Enzinger et al.) differing from other previously described soft-tissue tumors.

Clear cell chondrosarcoma. A case report with topographic analysis

A case of clear cell chondrosarcoma located in the right proximal end of the femur is presented. Radiologically, the tumor appeared as a large osteolytic lesion with mottled calcification resembling chondroblastoma. Histologically, the greater portion was made up of tumor cells with abundant clear cytoplasm and usually distinct boundaries, associated with areas of conventional chondrosarcoma. The proportion of the clear cell areas was about 60%, and they were mainly distributed along the tumor periphery. Moreover, myxoid chondrosarcoma-like areas, a feature not previously mentioned in clear cell chondrosarcoma, were observed, occupying about 10% of the tumor area.

Osteosarcoma with prominent epithelioid features

Osteosarcoma in the metaphysis to epiphysis of the left femur of a 17-year-old male is reported. The lesion appeared osteolytic with sclerotic foci on roentgenographs, accompanied by an extensive tumor shadow in the surrounding soft tissue. While 60% of the tumor was necrotic, histological examination of the remaining viable tissue revealed that it consisted almost entirely of a sheet of epithelioid cells, separated by thin, fibrovascular septa with an alveolar-like pattern, suggestive of metastatic carcinoma. Only a few areas were characterized by malignant osteoid tissue intermingled with the above cells, showing significant positivity for bone-specific alkaline phosphatase and 5'-nucleotidase, thus permitting a diagnosis of osteosarcoma. Autopsy findings revealed that the metastatic foci were histologically similar to those of the primary tumor. Electron microscopy revealed poor development of cytoplasmic organelles, supporting possible derivation from an osteoblastic cell lineage at an early stage.

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.

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)

Chordoma: an immunohistologic study

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

Mesenchymal chondrosarcoma of bone and soft tissue. A review of 111 cases

A series of 111 mesenchymal chondrosarcomas was reviewed. The ages of the patients ranged from 5 to 74 years, and approximately 60% of them were in the second and third decades of life. There was no significant sex predilection. Seventy-two tumors, including 5 that involved multiple skeletal sites, arose in bone. Thirty-eight tumors were found in extraskeletal sites. At initial diagnosis, multifocal involvement, both in bone and in soft tissue, was observed in one case. Roentgenographically, the lesions in bone frequently resembled ordinary chondrosarcomas, showing osteolytic and destructive appearances with stippled calcification. Tumors in extraskeletal sites were almost always identified as calcified masses. Histologically, a combination of cellular zones composed of undifferentiated small cells and chondroid zones typically presented a bimorphic appearance that was virtually pathognomonic in most cases. Ablative surgical treatment seemed to be the procedure of choice. The value of irradiation or chemotherapy (or both) was difficult to assess in the current study. Prognosis for patients with mesenchymal chondrosarcoma is usually poor, and long-term follow-up is necessary. In a group of 23 patients from the Mayo Clinic, the 5-year survival rate was 54.6% and the 10-year survival rate was 27.3%.

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.

Clonal analysis of the population of chondrocytes from the Swarm rat chondrosarcoma in agarose culture

Chondrocytes from the Swarm chondrosarcoma, a transplantable rat tumor, have been difficult to maintain in tissue culture for extended periods due to a time-dependent alteration of the culture to a more fibroblastic phenotype. This feature precluded the use of these cultures to examine chronic conditions that may affect cell metabolism, and the homogeneity or heterogeneity of the tumor cells within the culture population could not be examined. Use of suspension culture in agarose stabilized the chondrocyte phenotype, permitting long-term culture. Clones of tumor chondrocytes were established in agarose and were examined over 2-3 weeks for evidence that the cells were accumulating a proteoglycan-rich extracellular matrix, as determined by positive staining by Alcian blue, and were undergoing cell division. Nearly 90% of the cloned cells exhibited a prominent extracellular matrix by day 7 of culture and greater than 99% did so by day 14. Cell division did not occur to any great extent until days 6-7 of culture. After this lag, the cells appeared to undergo logarithmic growth, with a cell generation time of about 12 days. By 20 days of culture, between 80 and 90% of the initial clones contained multiple cells, indicating that nearly all the cells were in, or had entered, the cell cycle. These results suggest that the chondrocytes from the rat chondrosarcoma form a homogeneous cell population with respect to their ability to synthesize an extra-cellular matrix and divide.

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 of the os calcis: a case report

This case report of a myxoid chondrosarcoma of the os calcis is presented because of its rarity. The clinical, roentgenographic, and pathological features are discussed, and the difficulty in diagnosis is elaborated.

On the histogenesis of Ewing's sarcoma. An ultrastructural, immunohistochemical, and cytochemical study

Forty-two cases of Ewing's sarcoma (ES) have been studied with light microscopy during the 9-year period 1974 to 1982. Thirty-three patients had ES of bone, and in 9 patients the tumor was located in the extraskeletal soft tissues. Cases which fulfilled all the morphologic criteria were accepted as typical ES (31 cases), and those with some architectural or cytologic peculiarities were considered atypical forms of ES (11 cases). An immunohistochemical study (PAP method) to evaluate the presence in the tumor cells of the following markers: myoglobin, F-VIII-related antigen, lysozyme, alpha-1-antitrypsin, alpha-1-antichymotrypsin, and immunoglobulins (IgG, IgA, IgM, kappa and lambda light chains), was performed with negative results in all cases (paraffin blocks were available in 38 cases). The cytochemical study on fresh tissue imprints from five patients (PAS, Sudan Black, alpha-naphthyl acetate esterase, acid phosphatase, beta glucuronidase, myeloperoxidases, naphthol-AS-D chloroacetate esterase and alkaline phosphatase) gave no pattern of histogenetic significance, PAS being the best morphologic marker in tissue sections and touch preparations. A detailed ultrastructural study was performed on 34 cases; the main findings may be summarized as follows: medium sized cells, polygonal shape, oval nuclei, smooth nuclear envelope, abundant euchromatin, well-developed nucleolonema, scant membranous organelles, abundant hyaloplasmic glycogen, occasional lipid vacuoles, straight cell membranes, and primitive intercellular junctions. No differences were found between bone and extraskeletal ES; moreover, typical and atypical forms showed moderate quantitative differences with no qualitative change. The histogenesis is discussed; no functional or morphologic markers have been found to suggest the cell of origin; however, some cell lines may be excluded. It is the impression of the authors that they are dealing with a primitive noncommitted mesenchymal cell.

Human osteogenic sarcoma: fine structure of the chondroblastic type

The fine structure of representative regions of four chondroblastic osteogenic sarcomas was studied. These regions contained four morphologically distinguishable subtypes of chondroblastlike cells. In addition, multinucleated giant cells, fibroblastlike cells, and macrophagelike cells were present, along with small populations of unclassifiable cells forming at least two subgroups of cells likely to be of a neoplastic nature. With only one exception, all types of chondroblastlike cells were separated by wide zones of extracellular matrix. The large multinucleated cells showed a fine structure that differed from that seen in multinucleated giant cells of other tissues. The evidence suggested that the multinucleated cells in the chondroblastic osteogenic sarcomas were active in phagocytic functions. It is not clear whether or not they are neoplastic in nature. Osteoblastlike cells were not encountered in the chondroid areas of the osteogenic sarcomas studied. On the basis of the findings it is concluded that the observed fine structural polymorphism of the chondroblastlike cells may reflect differences in maturation and differentiation among these cells. The most well-differentiated cells (type 1) appear to be able to exert secretory functions.

Mesenchymal chondrosarcoma in the young

It has been almost a quarter of a century that this rare, still poorly understood and to date insufficiently studied, cartilage neoplasm was described. Based on 19 cases in the young representing 26 percent of chondrosarcoma patients under the age of 21 years, this study found equal sex distribution with the youngest patient being a 6-year old boy. Twelve lesions occurred between the ages of 16 and 21 years. All but one of the tumors arose in the skeleton with nearly half of them involving the lower extremity. Pain was inconsistent and rare at presentation in contrast to the regularity of swelling or a painless mass. Survival analysis revealed a 46 percent 2-year and a 35 percent 5-year survival rate, whereas at 10 years only 20 percent of the patients were still alive. This study attempts to establish the likeliest evolutionary pathway of neoplastic cell differentiation and traces the origin of this tumor to a neoplastic caricature of embryonal endochondral osteogenesis.