Cases reported "Skin Neoplasms"

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11/31. Identification of desmosomes in the granular cell tumor. Implications in histologic diagnosis and histogenesis.

    Electron-microscopic examination of a malignant granular cell tumor revealed cells with abundant granular and glycogen-containing cytoplasm and eccentric nuclei. Numerous junctional structures including desmosomes were identified between tumor cells which, moreover, displayed a pattern of gland formation with the presence of short microvilli in one pole of the cell. The presence of junctional structures may provide a feature for positive identification of this tumor by electron microscopy. The findings may also have implications to further our understanding of the histogenesis of this tumor. This case further raises the question of familiar occurrence of this tumor.
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12/31. Granular cell basal cell carcinoma.

    Granular cell basal cell carcinoma (BCC) is a rare histologic variant of BCC. In this, the third reported case, the tumor consisted almost entirely of granular cells. By electron microscopy, these cells were filled with pleomorphic lysosome-like granules lined by unit membranes and containing homogeneous or granular electron-dense bodies, membranous debris and amorphous material. The epithelial origin of the tumor was suggested by the characteristic light microscopic appearance of tumor cell islands with some areas of peripheral palisading, and was confirmed by electron microscopic features of numerous well-formed pentalaminate desmosome junctions and sparse cytoplasmic tonofilament bundles, some of which showed attachments to the desmosomes. Histochemical immunoperoxidase stains for lysozyme showed no cytoplasmic lysozyme activity, in common with other granular cell tumors, but ultrastructural examination did not reveal angulate bodies, in contrast to findings in non-epithelial granular cell tumors.
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13/31. Trabecular carcinoma of the skin. A histopathological study of two cases.

    The first two cases of trabecular carcinoma of the skin reported in israel are presented. On light microscopy, the tumors demonstrated a distinctive trabecular pattern, with cords of tumor cells embedded in the connective tissue stroma in the dermis. Dense-core neurosecretory granules, in association with formed desmosomes, were demonstrated by electron microscopy. This tumor may be misdiagnosed as lymphoma or metastatic anaplastic carcinoma, and awareness of its distinctive morphological features is necessary in order to arrive at the correct diagnosis.
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14/31. Solitary familial desmoplastic trichoepithelioma. A study by conventional and electron microscopy.

    Solitary desmoplastic trichoepitheliomas from a mother and two daughters were studied by conventional and electron microscopy. Differential diagnosis by conventional microscopy is briefly discussed. The lesions consisted of cords and nests of basaloid cells set in fibrotic stroma and confined to the dermis. In addition, each lesion contained horn cysts and focal areas of calcification. Horn cysts were occasionally identified in continuity with infundibulae of normal hair follicles. Semithin sections showed cords and nests of cells in continuity with the horn cysts. Ultrastructurally, a continuous basal lamina surrounded the cords of basaloid cells and connected to horn cysts. Individual cells contained tonofilaments and were attached to adjacent cells by desmosomes. hemidesmosomes were present at peripheral cell membranes bounded by basal lamina. There was no glandular differentiation. Our observations by electron and conventional microscopy support a conclusion that desmoplastic trichoepitheliomas are derived from hair appendages.
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15/31. Desmoplastic malignant melanoma: A light and electron microscopic study of two cases.

    This light and electron microscopic study of two recent cases of desmoplastic malignant melanoma (DMM) attempts to resolve the conflict in views regarding the nature of the cells responsible for the desmoplasia associated with this clinicopathologic entity. On the basis of evidence presented, it is concluded that the cells are dedifferentiated tumor cells with fibroblastic features and probably functions, rather than host engendered fibroblasts in response to invasive melanoma. The evidence includes: observation of macular desmosomes between tumor cells, an unheralded feature previously noted in amelanotic and melanotic melanomas; electron microscopic observation of fibroblast-like cells by others in spindle cell squamous carcinomas; and light microscopic features of malignancy including vascular invasion in one of the two cases. A reproducible light microscopic pattern diagnosis of this variant of malignant melanoma is reaffirmed in both cases.
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keywords = desmosomes
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16/31. Merkel cell tumor of the skin. Ultrastructural and immunohistochemical studies.

    A skin tumor of a 66-year-old female was investigated morphologically and immunohistochemically. The tumor was located within the dermis and comprised of rounded cells with scanty cytoplasm, which proliferated forming a small nest or trabecular arrangement. Electron microscopic observation indicated the presence of dense-core granules within the tumor cell cytoplasm suggesting that the tumor was derived from merkel cells. Occasionally clusters or bundles of the intermediate filaments were found in the perinuclear cytoplasm of the tumor cells. Each tumor cell was connected with desmosomes. Immunohistochemical staining with anti-keratin antiserum showed positive reaction at the perinuclear cytoplasm of the tumor cells indicating that the cluster of the microfilaments presumably contains keratin. Conversely S-100 protein was negative in the tumor cells. The results obtained strongly suggest that the tumor or Merkel cell was considered to be derived from the epidermal immature cells rather than from the neural crest.
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keywords = desmosomes
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17/31. Malignant hidroacanthoma simplex. A light microscopic, ultrastructural, and immunohistochemical study of 2 cases.

    2 cases of malignant hidroacanthoma simplex are reported. Prominent ultrastructural findings were sparse tonofilaments and villous-like, interdigitating cytoplasmic processes connected by small desmosomes. Positive intracytoplasmic stain for carcinoembryonic antigen was found in 1 case. Benign and malignant eccrine poromas and hidroacanthoma simplex appear to be related neoplasms on the basis of ultrastructural and immunohistochemical findings.
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keywords = desmosomes
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18/31. A light and electron microscopic study of bowenoid papulosis.

    Bowenoid papulosis of the genito-anal region was studied by light- and electron-microscopy. Histopathologically there was no difference between bowenoid papulosis and ordinary bowen's disease. Conspicuous ultrastructural findings included: great variation of intercellular spaces, decrease in intact desmosomes, aggregation of tonofilaments resulting in dyskeratosis, and two types of intracellular vacuolization probably caused by invagination of plasma membrane.
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keywords = desmosomes
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19/31. Trichilemmal keratosis (horn): a light and electron microscopic study.

    Three cases of trichilemmal keratosis (horn) were light microscopically examined and all showed numbers of U- or V-shaped epidermal proliferations which keratinized in a fashion either identical or similar to trichilemmal keratinization. Electron microscopy revealed both uneven and linear borders between the keratinized and the keratinizing cells with a few keratohyalin droplets, remnants of desmosomes, no marginal band in the horny layer, perinuclear vacuolation, few spherical bodies in the intercellular spaces (ICS) of the upper epidermis, and widening of the ICS of the lower epidermis. A number of electron dense spherical particles, 40-50 nm in diameter, were observed in nuclei of the upper epidermis. This suggests that ultrastructure of trichilemmal keratosis is similar rather to viral warts than to trichilemmal cysts, although there are close similarities between trichilemmal keratosis and cyst.
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keywords = desmosomes
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20/31. Linear unilateral basal cell nevus with comedo-like lesions.

    A 20-year-old woman had linear unilateral basal cell nevus with comedo-like lesions. Numerous papules were distributed on the left side of the upper aspect of the trunk in a zosteriform fashion. The indivisual lesions were hemispherical, pearly, and waxy tumors, some of which had central plugs. Histologic examination revealed polymorphous patterns that suggested that the tumor cells differentiated toward the apocrine glands, hair structures, and sebaceous glands. Ultrastructurally, the tumor strands were composed of fairly mature basal cells with well-developed tonofilaments and desmosomes.
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