Ultrastructure of human osteosarcoma. Malignant transformation of a multipotential connective tissue cell

Some observations on naturally occurring neoplasms of domestic fowls in the State of Victoria, Australia (1977-87)

In the 10 years to November 1987, 33 different types of naturally occurring neoplasms were diagnosed in 2281 domestic fowls submitted for necropsy examination. The most prevalent type was lymphoma (1825/2281 = 80%) including two cases in chickens from a flock free from Marek's disease virus, exogenous avian leukosis viruses and reticuloendotheliosis virus; the remaining lymphomas were diagnosed on gross and/or histological criteria as Marek's disease (1069) or lymphoid leukosis (754). Of the non-lymphoid neoplasms, leiomyomas of the ventral ligament of the oviduct (99) were the most common followed closely by metastatic abdominal adenocarcinomas (93) and haemangiomas or haemangiosarcomas (91). A large number of fibromas and fibrosarcomas (40), and a smaller number of myxomas and myxosarcomas (17) were observed. Three fibrosarcomas and two myxosarcomas were presented as metastatic abdominal neoplasms, and two fibromas and seven myxomas were found on the rostral extremity of the upper beak of hens, including five cases of myxoma from one flock. Other less prevalent neoplasms described were myelocytomas or myeloblastomas (12), avian keratoacanthomas (11), granulosa-theca cell tumours (11), oviduct adenomatosis and adenocarcinomas (10) and ovarian adenocarcinomas (8). Small numbers of some neoplasms or well-characterized variants were encountered, namely histiocytic sarcomas (5), lipomas (4), liposarcomas (2), reticulum cell sarcomas (3), plasmacytomas (3), intracutaneous keratinizing epitheliomas (3), feather folliculomas (2), proventricular adenomas (2), hepatocellular adenocarcinomas (2), cholangiocellular adenomas and adenocarcinomas (6), pancreatic adenocarcinomas (3), nephroblastomas (7), astrocytomas (5), pinealomas (3), Schwannomas (3) and multifocal melanomas (3). Single examples were found of osteoma, osteosarcoma, rhabdomyosarcoma, leiomyoma of the gizzard wall, intestinal adenocarcinoma, renal adenocarcinoma, adrenocortical adenoma and ultimobranchial cyst.

Ultrastructural signs of altered intracellular metabolism in acral persistent papular mucinosis

An asymptomatic 24-year-old woman presented with multiple discrete papules on the extensor surfaces of the hands and wrists. Light microscopy revealed focal increase in the amount of dermal fibroblasts as well as deposition of hyaluronidase-labile mucoid substance. The collagen and elastin were decreased. The changes were consistent with acral persistent papular mucinosis (APPM). In electron microscopy, the intercellular glycosaminoglycans showed small ruthenium red-positive granules and thin filaments indicating normal morphology. The fibroblastic cells, however, were conspicuously altered. Endoplasmic reticulum was dilated, cytoplasm contained large amounts of osmiophilic, concentric lysosomal structures, and there was distinct fibrous lamina in the nuclear membrane. It was concluded that the primary event in APPM probably affects the intracellular metabolism of the dermal fibroblast. The accumulation of lysosomal structures may be a distinct feature of APPM differentiating it from the other reactive cutaneous mucinoses, or it may only reflect nonspecific degeneration in a long-standing lesion.

Differential histologic diagnosis of osteoid. A study on human osteosarcoma collagen by the histochemical picrosirius-polarization method

Using only one histologic preparation and under the light microscope, the simple method described here permits a distinction between osteoid and other tissue components that can be mistaken for osteoid. Osteoid from both normal osteogenesis and osteosarcomas is disclosed by the picrosirius-polarization method as a three-dimensional network of randomly arranged, thin, short, weakly birefringent collagenous structures which shine against a dark background. These morphologic features can be used as a precise diagnostic criterion for the differential diagnosis between osteoid and other materials which resemble osteoid by other staining techniques. This precise characterization of osteoid is of great importance since the presence of osteoid is used as a criterion for the differential diagnosis of osteosarcomas. Not only does this method permit the precise characterization of osteoid but it is also useful for studying collagen distribution in osteosarcomas. In this regard the foregoing results agree with the immunofluorescence observations recorded in the literature.

Human osteogenic sarcoma: fine structure of hard tissue areas

The structure of hard tissue areas (with osteoid and calcified matrix) in 10 osteoblastic, chondroblastic, and fibroblastic osteogenic sarcomas was studied in the electron microscope. Neoplastic cells commonly associated with these areas and presumably actively involved in the production of hard tissue were osteoblast-like cells types 1 and 3, chondroblast-like cells type 1, and fibroblast-like cells, as defined and characterized in previous studies. The cells differed from those in soft tissue areas of osteogenic sarcomas in but one respect: they usually showed presence of irregular extrusions at their surfaces. Other types of osteoblast-like and chondroblast-like cells occurred rarely or not at all. Two types of multinucleated giant cells were recognized in these areas, one showing a fine structure reminiscent of that in osteoclasts, the other probably being of a neoplastic nature and engaged in the production of the calcifying matrix. The evidence suggested that neoplastic osteoblast-like, chondroblast-like, and fibroblast-like cells as well as certain multinucleated giant cells might all be involved in the mineralization process and/or the formation of osteoid in osteogenic sarcomas. Although phenotypically of highly variable appearance, all these different cells may thus functionally (and probably histogenetically) be closed related. The mineralization process in the tumor tissue appeared to be a modification of what occurs in normal ossification, possibly with an alternative or complementary pathway involving the production of spherical bodies with layered contents.

Biologic characterization of human bone tumors. II. Distribution of different collagen types in osteosarcoma--a combined histologic, immunofluorescence and electron microscopic study

Sixteen cases of typical highly malignant osteosarcoma were investigated by light, electron, and immunofluorescence microscopy to demonstrate the presence of collagen types I-III. It was shown that, in light-microscopically anaplastic areas of the tumor, collagen type III predominates, while only very few membranes of collagen type I are observed. Ultrastructurally, the cells are characterized by numerous free ribosomes in their cytoplasm and only a few membranes of granular endoplasmic reticulum (ER). In osteoblastic areas, collagen type I is increased, while type-III collagen is decreased. The cytoplasm of cells contains markedly more granular ER. An increasing mineralization of matrix is observed. In fibroblastic areas of the tumors, collagen types I and III are codistributed. Tumor cells have a fibroblast appearance with elongated nuclei and well developed granular ER. The chondroblastic areas, characterized by immature neoplastic cartilage, contain varying amounts of collagen type II. Chondroblast-like tumor cells have typical ring-shaped membranes of granular ER in their cytoplasm. The evidence of different collagen types in osteosarcomas lends additional support to the concept that a pluripotent mesenchymal cell is the stem cell of osteosarcomas.