Stem cell concept and heterogeneity of malignant soft tissue tumor--a challenge to reconsider diagnostics and therapy?

Synovial sarcoma: report of a series of 25 consecutive children from a single institution

BACKGROUND

The role of postoperative radiotherapy and adjuvant chemotherapy in the treatment of synovial sarcoma remains to be determined.

PROCEDURE

Twenty-five children were treated during a 23-year period with a multimodality approach. All of them had resection of the primary tumor (three amputations), followed by surgical retreatment in eight. Postoperative radiotherapy was delivered to 16 patients and adjuvant chemotherapy was given to 22.

RESULTS

At the time of the report, 19 patients were alive and without evidence of disease. Six developed distant metastases (one associated with local recurrence); five of them died of their disease and one was alive in complete remission at 4 years from relapse. With a median follow-up of 9 years (range 2-23), the survival and the event-free survival at 5 years were 80% (SE 8.2) and 74% (SE 9.2), respectively. All relapsing patients had been classified as T2B.

CONCLUSIONS

Multimodality treatment yielded satisfying survival results using limb-preserving surgery in most cases. Tumor size > 5 cm and invasiveness, which defined stage T2B, were the most important predictors of poor outcome. Evaluation of the role of adjuvant chemotherapy and radiotherapy awaits prospective studies, even if T2B patients, as well as children having nonradical surgery, seem worth managing by adjuvant treatments.

Malignant fibrous histiocytoma: histomorphological pattern or tumor type

During the past years MFH has obviously been used as a diagnostic waste basket for hard to classify tumours of all kinds. Immunohistochemistry revealed insights into cellular differentiation of neoplastic proliferations, also raising new questions because of unexpected antigen expression, as, for instance, cytokeratins in MFH. Thus, a number of tumours originally diagnosed as MFH could be reclassified, i.e., as leiomyosarcoma, melanoma or anaplastic carcinoma. Nevertheless, there remain a certain number of sarcomas which lack any evidence of special cellular differentiation. These proliferations of primitive mesenchymal or fibroblastic cells, often with a typical histological, storiform pattern, qualify as MFH. Using these strict criteria, the diagnosis of MFH will become rarer, though not obsolete (like hemaugioperizytoma years ago!).

Calcium pump expression in human bone and soft tissue tumours

Ninety-one cases of human bone and soft tissue tumours were studied for calcium pump expression by strepto-avidin-biotin immunohistochemical staining with a monoclonal antibody against sarcoplasmic reticulum calcium-ATPase (mAb6F5). Two out of 5 cases of embryonal rhabdomyosarcoma, 1 out of 5 cases of biphasic synovial sarcoma, 4 of 4 cases of chordoma and all of 3 chondrosarcoma cases were positive for mAb6F5. Although this novel monoclonal antibody can be used as a marker of myogenic tumours, the present positive result for endoplasmic reticulum calcium-ATPase (calcium pump) in other tumours including chordoma, chondrosarcoma and synovial sarcoma indicates a wider immunoreactivity. The findings further suggest that intracellular calcium may play an important role in cell proliferation and/or differentiation.

Rare tumors in childhood: pathological aspects. Experience of the Kiel Pediatric Tumor Registry

A wide variety of rare tumors can occur in childhood and adolescence. Tumors can be rare in any age group; common tumors of adults can appear in childhood and adolescence, and many rare tumors and tumor-like lesions show a predilection for younger age groups. Comparatively frequent tumors can present with rare histologic features or can occur in rare atypical locations, and, finally, seemingly common but, in fact, rare tumors have to be distinguished from truly common but rarely recognized tumors. Thus, the spectrum of rare tumors is broad, reflecting the fluent reality of life.

Synovial sarcoma in children and adolescents. A report from the Kiel Pediatric Tumor Registry

Of 49 cases of synovial sarcoma, which represent 5.8% of all soft tissue sarcomas with confirmed diagnosis in the files of the Kiel Pediatric Tumor Registry (Kiel, Germany), 35 occurred in patients up to the age of 18 years. The lower extremities were the most common. The 35 cases included 21 biphasic and 14 monophasic fibrous synovial sarcomas. The different cell types constituting synovial sarcoma could be demonstrated by conventional light microscopic study, but more readily so by immunohistochemical study, particularly when antibodies against cytoskeletal components were applied. Aberrant antigen expression was noticed for the neural markers, protein S-100, and neuron-specific enolase. Moreover, four tumors were positive for Ki M7. Collagen type IV was found in all tumors tested. For the 20 patients enrolled in the Cooperative Soft Tissue Sarcoma Study of the German Society of Pediatric Oncology (GPO) the survival rate at 7 years is 63%. When five patients with initial recurrence are excluded, the survival rate is 72%. It is concluded that immunohistochemical study is useful in the diagnosis and differential diagnosis of synovial sarcomas despite certain limitations. Multimodality treatment approach has improved the overall prognosis. There is no relationship between histologic subtype and prognosis according to the classification scheme employed in this study.

Cellular heterogeneity. Explanation for changing of tumor phenotype and biologic behavior in soft tissue sarcomas

Many human soft tissue sarcomas are known to show variable structures in a given tumor and to be able of changing the histological feature during the course of the disease. These facts prompted an experimental study in order to ascertain if by use of long-term cultures of an established rat fibrosarcoma cell line (RFS) in respective inoculation tumors a histological picture different from the original fibrosarcoma could be produced. It was found that inoculation tumors generated by later subcultures partly corresponded to tumors with features of malignant histiocytomas and malignant fibrous histiocytomas. In a further experiment we attempted to initiate metastatic dissemination of a primarily non-metastasizing xenotransplanted RFS sarcoma in nude mice. By repeated diminution operations comparable to inadequate tumor surgery in human metastasis formation in lung parenchyme was attained. Taking into account cellular heterogeneity as basically responsible for the phenomena observed, different causal aspects concerning the experimental results are discussed. We deduce from our findings that the concept of histogenetic classification of soft tissue sarcomas should be replaced by an interpretation according to the actual differentiation. This also applies to malignant fibrous histiocytomas which are at least in part mesenchymal tumors and not descendants of mononuclear phagocytic cells and may originate by a dedifferentiation process of otherwise defined sarcoma types.

Experimentally induced metastases of malignant fibrous histiocytomas xenotransplanted into nude mice from an established sarcoma cell line (RFS)

An experimental approach for inducing metastases from xenotransplanted malignant fibrous histiocytomas in nude mice is presented. Malignant fibrous histiocytomas were generated by inoculation of an established cell line (RFS) in the back of 16 nude mice. 7 nude mice were subjected to diminution operations carried out twice and three times, respectively, 6 out of these animals developed metastases, whereas no metastases were found in the inoperated control group (9 mice). The metastasis formation is explained by sarcoma heterogeneity, some factors which might contribute to the phenomenon of tumor dissemination are discussed.

Epithelioid sarcoma in children and adolescents. An immunohistochemical study

Six cases of epithelioid sarcoma were studied by conventional light microscopy and immunohistochemistry. The six cases account for 1.4% of the 417 cases of soft tissue sarcoma collected at the Paediatric Tumor Registry, Kiel. The average age of the five male and one female patient was 10.8 years (median: 13 years). Particular clinical findings included the location of the tumours; three were found in the pelvis, two in the head and neck, and one in the hand. Four patients are living without disease, and one patient died of disease three years after diagnosis. Histologically, four of the six tumours revealed multinucleated giant cells. Immunohistochemically using a panel of mono- and polyclonal antibodies all cases stained positively for vimentin, cytokeratin, epithelial membrane antigen (EMA), and human milk fat globulin (HMFG-2). Five cases were positive for neuron specific enolase (NSE), and three stained positively for protein S-100. A positive reaction for alpha-1-antichymotrypsin was noted in two cases. These immunohistochemical findings attest to the multidirectional differentiating capabilities of epithelioid sarcoma and support the concept of derivation from a multipotent mesenchymal stem cell.

Ultrastructural ultracytochemical investigation of human gastric carcinomas

We describe the ultrastructure of various types of gastric carcinoma cells as well as their histochemical properties as visualized at the electron-microscope level. The histochemical properties of tumour cells were compared with those of homologous normal epithelial cells. The localization and activity of ATPase, IDPase, acidic phosphatase and alkaline phosphatase as well as of the oxidoreductases (cytochrome oxidase, succinate dehydrogenase and NADH-dehydrogenase) were studied. Our findings demonstrated that, in tumour cells, a complicated process of structural-functional restructuring takes place. It seems that a number of ultracytochemical properties may be preserved or may disappear altogether; also, such properties may become enhanced or weaker. This heterogeneity of the histochemical properties of tumour cells is discussed with regard to the role of the stem (polypotent) cell in the process of the histogenesis (cytogenesis) of human gastric carcinomas.