Experimentally produced synovial sarcomas

A note from history: Landmarks in history of cancer, Part 6

In the 3 decades from 1940 to 1970, the United States became the nucleus for research, diagnosis, and treatment of cancer. The discovery of anticancer drugs, and the clinical demonstration that chemotherapy and radiation can cure cancer and have the ability to prevent recurrence of cancer, were incontrovertibly the most remarkable groundbreaking events. Consequently, the trend of less surgery and more multimodality therapy began. The introduction of radioautography, mammography, ultrasonography, computed tomography, Papanicolaou smear, and other novel laboratory tests furthered early detection of cancer and refined accurate diagnosis. The unequivocal linking of lung cancer to cigarette smoking made medical history. The delineation of the potential role of oncogenes adduced new thoughts about oncogenesis and cancer prevention, and pathologists finalized the classification and nosology of tumors. Finally, it is worth noting that although more advances were made in the detection, diagnosis, and treatment of cancers than any other period in history, the overall mortality rate of patients with cancer remained high and unchanged.

Transdifferentiation of neoplastic cells

Transdifferentiation is a process in which a stable cell's phenotype changes to that of a distinctly different cell type. It occurs during certain physiological processes and leads to transition of tumor cell phenotypes. The latter process includes neoplastic epithelial-epithelial transition, neoplastic epithelial-mesenchymal transition, neoplastic mesenchymal-epithelial transition and transition between non-neural and neural neoplastic cell. This phonomenon is exemplified in some origin-debated tumors, such as carcinosarcoma, pleomorphic adenoma, synovial sarcoma, Ewing's/pPNET, and malignant fibrohistiocytoma. We propose that differentiation disturbance of cancer cells should include not only undifferentiation and dedifferentiation, but also transdifferentiation as well. Tumor cell transdifferentiation may be influenced or determined by cellular genetic instabilities, proliferation and apoptosis, as well as by extracellular matrix and growth factors.

Poorly differentiated synovial sarcoma: immunohistochemical distinction from primitive neuroectodermal tumors and high-grade malignant peripheral nerve sheath tumors

Synovial sarcoma is a relatively common sarcoma in adults, which in its classic bimorphic form infrequently poses a diagnostic problem. Monomorphic spindled variants, as well as the less common poorly differentiated variants, may be confused with other soft-tissue sarcomas; the poorly differentiated variant (PDSS), in particular, may be histologically indistinguishable from other small, blue, round cell tumors, including primitive neuroectodermal tumors (PNETs). Detection of the synovial sarcoma-associated t(X;18) by either cytogenetic or molecular genetic approaches may be necessary to confirm the diagnosis of synovial sarcoma in difficult cases. We evaluated 10 cases of PDSS from eight patients using a panel of antibodies (including those to intermediate filament proteins, nerve-sheath associated markers, and neuronal and neuroectodermal associated markers) in order to better establish the immunophenotype of this tumor and to help distinguish it from the tumors with which it may be confused, particularly PNETs and high-grade malignant peripheral nerve sheath tumors (MPNSTs). Our results showed PDSS to have significant immunophenotypic overlap with both PNETs and MPNSTs. In most instances these three entities may be differentiated by a panel of antibodies that should include those to both low and high molecular weight cytokeratins, epithelial membrane antigen, type IV collagen, CD99, CD56, and S-100 protein. Our results also suggest that synovial sarcoma may be a tumor showing combined neuroectodermal and nerve sheath differentiation--perhaps because of translocation-associated expression of specific proteins--rather than a carcinosarcoma of soft tissues or a tumor of specialized arthrogenous mesenchyme.

Metal carcinogenesis in total joint arthroplasty. Animal models

As early as 1956, laboratory investigations into the carcinogenicity of modern dental and orthopaedic alloys were undertaken. Such studies were prompted by the observation that workers, particularly in nickel and chromate refining, had increased risks of nasal and lung tumors. For the past 25 years, sporadic case reports have documented the development of malignant neoplasms proximate to an orthopaedic implant. Although the results of epidemiologic studies have not shown an excessive number of tumors in patients receiving stainless steel or superalloy implants, the possibility of carcinogenesis, given the corrosive environment in which metal implants exist, has prompted ongoing laboratory studies. Leaching of metal ions from implants, the synovial processing of metallic wear debris, and the effects of exposure to intraarticular metal particles have been the subjects of numerous laboratory studies. The results of these studies are summarized and recommended parameters for future laboratory investigations are given.

Intraarticular carcinogenesis bioassays of CoCrMo and TiAlV alloys in rats

Wear-debris powders of cobalt-chromium-molybdenum (CoCrMo) and titanium-aluminum-vanadium (TiAlV) alloys, which are widely used for orthopedic implants (eg, hip and knee prostheses), were tested for carcinogenic activity following intraarticular administration (20 mg/rat) to groups of 44 male Fischer-344 rats (Charles River Breeding Laboratories, North Wilmington, MA). Control groups received similar intraarticular injections of either a noncarcinogen (manganese powder, negative control rats) or a potent carcinogen (nickel subsulfide powder, positive control rats). The experimental groups of 8-12 rats were observed for 24 months after injection. No local tumors developed at the injection site in the negative control rats or in rats that received the CoCrMo or TiAlV powders; poorly differentiated or pleomorphic sarcomas developed at the injection site in 10 of the 12 positive control rats that were treated with nickel subsulfide. Incidences of primary tumors distant from the injection site did not differ significantly among the experimental groups. This study shows that, under experimental conditions, any carcinogenic activity of CoCrMo or TiAlV wear-debris powders is weak in comparison to nickel subsulfide. Based on this study and observations in other laboratories, intraarticular administration of test materials to rats provides a practical, reliable, and biologically relevant method for carcinogenesis testing of biomaterials used for orthopedic implants.

Synovial sarcoma in a dog

Synovial sarcoma is an uncommon malignant tumour of mesenchymal origin, occurring mainly in the vicinity of a joint. Subsequent invasion of the joint and adjacent bones may occur. Less frequently the tumour may be localized in soft tissues remote from joints. Synovial sarcoma usually affects male middle-aged dogs of large breeds. The rate of tumour growth can vary from very slow to very rapid. The tumour is usually poorly defined and infiltrates the deeper structures. Metastasis and recurrence are common. Wide-field surgical excision of the tumour or amputation of the affected limb are the most frequently used forms of treatment. In the present case the dog, a 7-year-old male Alsatian, had a slowly growing tumour in the vicinity of the hip joint, bilaterally. There was no involvement of the bones surrounding the tumour. Surgical resection was performed and one year later the dog was reported to be normal.

Induction of soft tissue tumours in F344 rats by subcutaneous, intramuscular, intra-articular, and retroperitoneal injection of nickel sulphide (Ni3S2)

The carcinogenicity of nickel sulphide (Ni3S2) injected into subcutaneous (s.c.), intramuscular (i.m.), or retroperitoneal intrafat (i.f.) tissue, or the intra-articular space (i.a.) of male F344 rats was studied. Rats were given a single injection of 0.5 mg of Ni3S2 and were observed for 48 weeks. Malignant soft tissue tumours were induced in 18/19 rats (95 per cent) by s.c. injection, 19/20 rats (95 per cent) by i.m. injection, in 16/19 rats (84 per cent) by i.a. injection, and in 9/20 rats (45 per cent) by i.f. injection of Ni3S2. The i.f. injection of Ni3S2 resulted in a lower tumour incidence and the appearance of tumours 10 weeks later than its injection by other routes. The tumours were examined histologically, ultrastructurally, and immunohistochemically with antibodies against desmin, vimentin, and cytokeratin. The 62 tumours induced by injection of Ni3S2 by different routes were identified as rhabdomyosarcomas (RMS, 35), malignant fibrous histiocytomas (MFH, 18), fibrosarcomas (FS, 5), and unclassified sarcomas (4). All 19 tumours induced by i.m. injection of Ni3S2 were rhabdomyosarcomas; those induced by s.c. or i.f. injection were mainly MFHs. However, a number of RMSs were also found in groups that received i.a., s.c., and i.f. injections; five FSs also developed in these groups. Four sarcomas induced by s.c. and i.a. injections were not classified. No synovial sarcoma developed.

Malignant fibrous histiocytoma induced by intra-articular injection of 9,10-dimethyl-1,2-benzanthracene in the rat. Pathological and enzyme histochemical studies

Malignant fibrous histiocytoma (MFH) was produced by injection of 9,10-dimethyl-1,2-benzanthracene (DMBA) into the rat knee joint. The tumor was observed in or around the knee in nearly all the animals 13 to 36 weeks after the initial DMBA administration. Histologically, these lesions were of the storiform-pleomorphic type (39/58, 67.2%), myxoid type (9/58, 15.5%), or giant cell type (8/58, 13.8%). Six cell types reported in human MFH were confirmed and phagocytosis of 0.81-micron latex particles by histiocyte-like cells was noted by electron microscopic examination. Acid phosphatase, beta-glucuronidase, and alpha-naphthyl acetate esterase were positive in enzyme histochemical examinations. Acid phosphatase activity was electron microscopically noted primarily in the lysosomes and the Golgi apparatus of the histiocyte-like cells. Cells from the storiform-pleomorphic (M1) and myxoid (M2) type tumors were serially transplanted subcutaneously in the back of the rats, and are now at the thirtieth and fortieth passage, respectively. They also were studied by enzyme histochemical and electron microscopic techniques. Our observations suggested an undifferentiated mesenchymal cell origin of MFH. Transplantable MFH can be produced in rats by intra-articular injection of DMBA, and lesions thus produced are a useful experimental model for the investigation of the histogenesis and the effect of chemotherapy of MFH.

Experimental-induced sarcomas after intra-articular injection of 9-10-dimethyl-1-2-benzanthracene

The authors describe an experimental study on rabbits whereby the development of sarcomas was induced following injection into the knee joint with 9-10-dimethyl-1-2-benzanthracene. The results of the experiment are in contrast to those of other authors as no "synovialoma" or synovial sarcoma developed but only morphological patterns which might belong to malignant fibrous histiocytoma and occasionally fibrosarcoma. In accord with our results the hypothesis is discussed that all malignant mesenchymal neoplasias result from a not clearly identifiable pluripotent mesenchymal stem cell.

Ultrastructure of human tendon sheath and synovium: implications for tumor histogenesis

Normal human tendon sheath and synovium were studied by scanning an transmission electron microscopy. The lining cells of the two tissues appear to be identical ultrastructurally. The most superficial cells (B-cells) possess long cytoplasmic extensions that clothe the membrane surface. Intermingled with deeper B-cells are the so-called A-cells, which have similar cytoplasmic features but lack long processes and instead have many filopodia. the frequent occurrence of intermediate forms indicates that the two cells form part of a morphologic spectrum. Comparison with cells of tumors that have been ascribed to synovium or tendon sheath (synovial sarcoma, epithelioid sarcoma, clear cell sarcoma) do not reveal any close similarities that might support a histogenetic relationship.

Synovial sarcoma of the abdominal wall. Light microscopic, histochemical and electron microscopic investigations

A synovial sarcoma of the abdominal wall in a 56-year old woman showed the typical features of this tumor type. Histologically a characteristic biphasic cellular pattern with epithelium-like cell complexes and sarcomatous spindle cell areas was found. The histochemical examination revealed that tumor cells synthesize glycoproteins and weakly acid glycosaminoglycans (mainly hyaluronic acid). Electron microscopically the tumor cells in epithelium-like cell islets were sometimes arranged in gland-like formations with microvilli at the luminal side, specialized intercellular junctions and a peripheral basement membrane-like condensation of the ground substance. There was no fundamental cytological difference between cells of epithelium-like and spindle cell areas. Generally the tumor cells imitated cells of the synovial membrane and we found no evidence for origin from cells of the nerve sheath. Because of the submicroscopic relationship and histochemical similarities of synovial sarcomas and mesotheliomas we suggest that they should be united in a group of sarcomas with possible biphasic cellular pattern, while preserving their clinicopathologic definition.

A malignant tumor of the vagina resembling synovial sarcoma: a light and electron microscopic study

A malignant tumor arising in the upper lateral vaginal mucosa in a 24-year-old white woman, hitherto undescribed in the literature, was studied by light and electron microscopy. The main part of the tumor was epithelioid, forming a tubular or acinar pattern. At the periphery, the tumor cells were more spindly and formed sheets resembling fibrosarcoma. The tumor cells contained occasional material positive for mucicarmine, alcian blue, and PAS stains, and the nests of the cells forming acini were surrounded by reticulin fibers. The tumor ultrastructure consisted of a single type of cell with large cytoplasmic vacuoles and occasional perinuclear intracytoplasmic filaments. Slender long microvilli projecting into the lumina were also characteristic. Basal laminae were occasionally present around the acini. The findings suggested that the tumor was of mesenchymal origin, closely related to synovial sarcoma.

Synovial sarcoma of the anterior abdominal wall

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