In vitro differentiation of myxoid liposarcomas maintained in organ culture system.

Liposarcoma falls into the differential diagnosis of myxoid malignant mesenchymal tumors. On the other hand, its relation with white or brown fat is controversial. Two cases of liposarcoma have been studied by organ culture, a method which provides cell and tissue redifferentiation in vitro. Both cases developed successively cytoplasmic glycogen granules and lipid droplets as well as a single lipidic vacuole in the late phase of cultivation as a marker of fat differentiation. Our results support the possibility of identifying myxoid liposarcomas as well as their origin from white fat tissue.

Hemangiopericytoma in a male breast. Report of a case with cytologic, histologic and immunochemical studies.

A hemangiopericytoma in a male breast was studied by fine needle aspiration (FNA) biopsy. The FNA smears contained tissue clumps showing knob-like formations of atypical cells, spindle-shaped cells and fragments of capillaries lined by normal endothelial cells. Immunocytochemical study showed a positive reaction for vimentin, but a negative reaction for desmin and keratin. Staining for Factor VIII was positive only in the capillaries and endothelial cells. The cytodiagnosis was "mesenchymal tumor." Histopathologic study of the mastectomy specimen made the final diagnosis of hemangiopericytoma. While FNA cytology and immunocytochemistry cannot make a definitive diagnosis of this rare vascular tumor, they can be decisive in planning the surgical treatment, as in the present case.

Distinctive growth patterns between cerebral and cerebellar astrocytomas--a tissue culture study.

Astrocytomas have been alternatively considered as a single entity with topographical variabilities or as two different tumours--cerebral astrocytomas and mid line-cerebellar, astrocytomas. Twenty-two astrocytomas, 13 of the cerebral hemispheres, six cerebellar, two brain stem and one of spinal cord, have been studied by short-term tissue cultures. Two distinctive growth patterns have been found. Cerebral astrocytomas grew in the first week as radially arranged bipolar cells and subsequently by multipolar astrocytes in a reticular pattern. On the other hand, astrocytomas of the cerebellum, brain stem and spinal cord showed radial growth of long bipolar cells which persisted during the first 2-3 weeks. Only in the fourth week did a reticular pattern develop, but most of the cells remained bipolar. After the fourth week, a small number of multipolar astrocytes appeared and in two cases Rosenthal fibres were found. It is thus suggested that astrocytomas may be subdivided into two entities, those of the cerebral hemispheres and others in the cerebellum, optic nerve, brain stem and spinal cord which can be grouped as midline astrocytomas.

The astrocytic nature of glioblastoma demonstrated by tissue culture.

Forty-eight cerebral astrocytomas and glioblastomas were studied by tissue culture for two purposes: (a) the establishment of a definite growth pattern of cerebral astrocytomas and (b) the comparison of this growth pattern and that of glioblastomas. According to the grade of malignancy the series was divided into four groups: low-, middle-, and high-grade astrocytomas and undifferentiated glioblastomas. All the astrocytomas showed the same growth pattern with two successive phases. First, bipolar cells in radial arrangement emigrated from the explant, whereas in the last weeks, multipolar astrocytic-like cells in reticular arrangement predominated. The more malignant the cases, the more prolonged the bipolar phase, with retardation of the development of multipolar cells. Glioblastomas showed the same behavior with maximal persistence of the bipolar phase. On this basis, we believe that (a) cerebral astrocytomas have a characteristic behavior in vitro and (b) the glioblastoma is an astrocytic tumor showing maximal dedifferentiation.

Malignant fibrosarcomatous mesothelioma and benign pleural fibroma (localized fibrous mesothelioma) in tissue culture: a comparison of the in vitro pattern of growth in relation to the cell of origin.

Two cases of fibrous mesothelioma are presented. The first is a malignant tumor containing bundles of spindle-shaped cells with a dense reticulin network and nests of epithelial-like cells. The second is a benign tumor made up of spindle-shaped cells arranged in bundles with abundant reticulin and collagen fibers. Tissue culture in the first case revealed plagues similar to those formed by epithelial tumors. The second case had a fibroblastic pattern with single isolated spindle-shaped cells. These findings confirmed the mesothelial nature of fibrosarcomatous mesothelioma and supported the view that the so-called localized fibrous mesotheliomas could be fibroblastic neoplasms derived from the submesothelial connective tissue.

The nature of macrophages (foam cells) in neurinomas. Tissue culture study.

Fourteen cases of neurinomas of variable location are studied by tissue culture technic in an attempt to typify the foam cells as primary or superimposed elements in the tumor population. Our results demonstrate that the "in vitro" behavior of the neurinomas is constant and characteristic and that three cell types are found in them: fusiform, star-shaped cells and macrophages. There appears that the macrophage is an evolutive aspect of the star-shaped cells and probably of the fusiform one. On this basis, macrophage and foam cells of neurinomas must be considered as primary.