Liver angiosarcoma and hemangiopericytoma after occupational exposure to vinyl chloride monomer.

Various malignant tumors of the liver, especially liver angiosarcoma, have been described after occupational exposure to vinyl chloride monomer. We present the case records and pathologic findings of two plastic industry workers who had been exposed to high concentrations of vinyl chloride. These workers developed hepatic neoplasms, angiosarcoma, or hemangiopericytoma. We discuss the histogenesis of these tumors; the common vascular origin and the mutual transformation of these two tumors suggest that the hemangiopericytoma may also have developed during occupational exposure to high concentrations of vinyl chloride monomer.

Exposure to polymeric materials in vascular soft-tissue sarcomas.

UNLABELLED: Known etiologic factors related to endothelial angiosarcomas are exposures to arsenic, thorium dioxide, therapeutic irradiation, and certain congenital diseases. Little is known on the etiology of hemangiopericytomas. Since 1974, several reports have appeared on a distinct relationship between the exposure to vinyl chloride monomers and angiosarcomas of the liver. The early reports on this matter provided the reason to collect the occupational histories of vascular sarcomas accumulated since that time. METHODS: Data on the occupational histories of patients with different forms of angiosarcomas, treated between 1975 and 1995 in two institutions, were prospectively collected and analyzed. In this personal series the only selection criteria were the referral of patients for postoperative or palliative irradiation and their personal care by the author. FINDINGS: Among 21 adult cases of vascular sarcomas there were 4 patients with occupational exposure to vinyl chloride (VC) either alone or together with other artificial polymers. Seven other patients showed exposure to several plastics or resins other than VC. Altogether, 11 of 21 (52%) of the explored patients were found to have been exposed to artificial polymeric materials over a mean period of 18 years. The patients without such exposure were 4 farmers, 2 house-wives, and 1 woodworker, telephonist, mason, and inland revenue official, respectively. Two cases were radiation-induced. The series contained no angiosarcoma of the liver. INTERPRETATION: This study offers new evidence of the occurrence of vinyl-chloride-induced angiosarcomas outside the liver and confirms observations that have previously been published in case reports. Moreover, it may be suspected from this analysis that polyvinyl chloride and its monomers are not the only polymeric materials that may contribute to an induction of angiosarcomas in humans. Repeated occupational histories have to be taken from the patients to achieve data of the greatest value, since there are many professional activities that do not primarily lead to the assumption of specific exposure to polymeric materials.

Spongiotic pericytoma: a benign neoplasm deriving from the perisinusoidal (Ito) cells in rat liver.

Spongiosis hepatis has been known for some time to develop frequently in livers of rats and fish treated with hepatocarcinogens and was considered to derive from the perisinusoidal (Ito) cells (PSC). Using rat liver treated with N-nitrosomorpholine at different dose levels, we studied the cellular composition and origin as well as the proliferation kinetics of spongiosis hepatis by immunohistochemical demonstration of desmin, vimentin, and alpha-smooth-muscle actin, and by autoradiographic determination of [3H]-thymidine incorporation, respectively. The vast majority of the cells forming spongiosis hepatis were positive for desmin and vimentin but negative for alpha-smooth-muscle actin, confirming the cellular origin of spongiosis hepatis from PSC. In addition, immunohistochemical demonstration of desmin and vimentin revealed that spongiosis hepatis is an integral part of larger lesions consisting of focal PSC aggregates. These aggregates show a significantly increased incorporation of [3H]-thymidine compared with PSC in the extrafocal tissue and in the liver tissue of untreated control animals. In stop experiments, this increased labeling index was maintained many months after withdrawal of the carcinogen, in line with the earlier observation of a progressive behavior of spongiosis hepatis. We conclude that PSC may give rise to proliferative lesions appearing as PSC aggregates associated with more or less pronounced spongiosis hepatis. The persistence, the proliferative activity, and the slow expansive growth of these lesions suggest a benign neoplastic behavior. We therefore propose to classify these lesions as spongiotic pericytoma. Malignant tumors possibly originating from spongiotic pericytoma should consequently by classified as perisinusoidal (Ito) cell sarcomas.

Intermediate filament reactivity in hyperplastic and neoplastic lesions from medaka (Oryzias latipes).

To determine if hyperplastic and neoplastic lesions from medaka showed similar immunoreactivity to intermediate filament antibodies as the tissues of origin, two week old medaka were exposed to 10 or 20 mg/L of methylazoxymethanol acetate for two hours and transferred to clean water for up to six months. Using a streptavidin peroxidase method, paraffin embedded Bouins fixed neoplasms were incubated with cytokeratin, vimentin, or neurofilament antibodies. Like their nonneoplastic cellular counterparts, hepatocellular carcinoma, pancreatic acinar carcinoma and mesenchymal neoplasms including hemangioma and hemangiopericytoma reacted negatively to cytokeratin antibodies. Cholangiocarcinoma, mesothelioma, and proliferative lesions containing biliary epithelial cells reacted positively to cytokeratin antibodies. All neoplasms and proliferative lesions were negative with vimentin and neurofilament antibodies. These data indicate that while some epithelial neoplasms showed cytokeratin reactivity similar to the parent tissues, additional markers are needed to identify mesenchymal tissues and neoplasms.

Ultrastructure of hepatic hemangiopericytoma in the medaka (Oryzias latipes).

The histologic and ultrastructural features of hepatic hemangiopericytoma from a medaka (Oryzias latipes) exposed for 48 hr to 400 mg/liter of diethylnitrosamine at 14 days of age are described. The predominant histologic pattern was of spindle-shaped cells forming numerous whorls around central capillaries, vacuolated areas, or necrotic debris. The predominant cell type was a spindle-shaped cell with oval nuclei, elongated cell processes, and abundant organelles converging upon normal appearing capillaries. Occasionally, however, they converged upon cells swollen with cytoplasmic filaments and/or containing large fenestrated or debris-filled cytoplasmic vacuoles. These features were reminiscent of endothelial cells undergoing intracellular canalization seen in angiogenesis or neovascularization. Individual capillaries were also seen in the mass independent of whorls. It was not clear, as is the case in man, if capillary formation was an integral part of the neoplastic process or a reactive response. Although the liver is an unusual location for hemangiopericytoma in man, many of the cellular features in the fish tumor were similar to the human tumor. The ultrastructural characterization of tumor cells in fish carcinogenesis correlated with histologic patterns of growth will expand our understanding of how fish cells respond when transformed, and augment the development and use of aquatic bioassays for carcinogenesis research.

N-nitrosodiethylamine-induced hepatocarcinogenesis in estuarine sheepshead minnow (Cyprinodon variegatus): neoplasms and related lesions compared with mammalian lesions.

Groups of estuarine sheepshead minnows (Cyprinodon variegatus) were exposed to approximately 57 mg N-nitrosodiethylamine [(DENA) CAS: 55-18-5]/liter for 5-6 weeks. Exposure was stopped and the fish were then transferred to clean, flowing seawater. Induced liver lesions were studied in periodic samples of fish taken during the next 140 weeks of holding. Lesions found following exposure were early altered basophilic and eosinophilic foci, oval cell hyperplasia, clear cell foci, neoplastic nodules, hepatocellular carcinomas, cholangiolar carcinomas, possible pericytomas originating in liver, hemangiopericytomas, spongiosis hepatis, and cholangiofibrosis. The relative prevalence of these lesions was given. Most of these lesions morphologically were compared to their counterpart lesions in the rat. Certain lesions in our fish such as hepatocellular carcinomas, cholangiolar carcinomas, pericytomas, hemangiopericytomas, spongiosis hepatis, and cholangiofibrosis have apparent similar cellular origins and morphogenesis to those lesions in rats and perhaps in other mammals. Spongiosis hepatis in the sheepshead minnow apparently arises from perisinusoidal cells and may be a neoplasm of this cell type. The general similarity of response to DENA in sheepshead minnows and rats suggests that this fish has promise as a model subject for studying some hepatocarcinogens and as a sentinel organism for detecting hepatocarcinogens in contaminated coastal waters.

Transplantable chemically-induced liver tumors in the viviparous fish Poeciliopsis.

Transplantation of five liver tumors induced with the chemicals diethylnitrosamine (DEN) and 7,12-dimethylbenz[a]anthracene (DMBA) in small live-bearing fish of the genus Poeciliopsis is reported. Five permanent strains representing three distinct tumor types were established in isogenic hosts. Histological characterization of hepatocellular carcinoma, hemangiopericytic sarcoma, and cholangiocarcinoma and the development of the neoplasms in host fish is presented. Transplantability of the experimental liver tumors provides evidence of their malignant nature. Metastasis of the hepatocellular carcinoma occurred from tumor implants in the dorsal musculature or peritoneal cavity and from the hemangiopericytic sarcoma implanted in the intraperitoneal cavity.

Hemangiopericytoma of the bladder after polyvinyl alcohol exposure.

A patient with hemangiopericytoma of the bladder following intensive exposure to polyvinyl alcohol is reported. Some early studies on polymer carcinogenesis are reviewed and recent work on vinyl chloride as a mutagen and potent carcinogen is cited. The need for epidemiologic and animal studies of other monomers is presented.

The histological appearance of tumours derived from rat embryo cells transformed in vitro spontaneously and after treatment with nitrosomethylurea.

Wistar rat embryo cells were treated in vitro with either 25 µg/ml of nitrosomethylurea (NMU) or phosphate buffered saline. Both groups showed morphological transformation by the 13th passage but their ability to grow in soft agar did not occur until at least passage 23; plating efficiencies indicated that NMU had reduced transformation. However, both control and treated cells gave rise to fibrosarcomata after similar latent periods following inoculation into syngeneic recipients. The fibrosarcomata had "myxoid" and "leiomyomatous" areas, and two resembled haemangiopericytomata; for the most part the tumours were transplantable. Inoculation of cloned NMU-treated cells produced fibrosarcomata with a high proportion of giant cells but only after a very long latent period. No virus particles were detected in tumour samples by electron microscopy.