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Query: UMLS:C0025202 (melanoma)
 69,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The extensive use of the single technic of immunofluorescence has resulted in the detection of an array of melanoma-specific antigens. Those antigens residing in the cytoplasm of the melanoma cell have been shown to cross-react across various melanoma cell lines in tissue culture, as well as across all fresh tumor cells isolated directly from patients. The ubiquitous nature of this antigenic activity, as defined by immunofluorescence, suggests that the presence of this activity may be important diagnostically. Isolation of one or more antigens from the cytoplasm, however, requires the development of an assay for antigenic activity in cell fractions. Data presented here indicate that passive hemagglutination provides as effective a means of visualizing antigenic activity as does immunofluorescence. Evidence showing that melanoma-specific antigenic activity is present as a soluble component in the cytosol and as a membrane-associated component of the endoplasmic reticulum is also presented.
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PMID:Hemagglutination as an alternate technic for the detection of melanoma-specific cytoplasmic antigens. 32 29

Conley et al., in 1971, described a special type of melanoma characterized by a superficial melanic lesion at the onset; repeated local relapses as subcutaneous tumorations with an histological picture closely resembling an atypical fibroxantoma or fibrosarcoma. After a review of all the published material the autors presents a personal case with the clinical, histological and evolutive characteristics of this disease. The most interesting findings of the published case are the following: The special stains for the melanocytes (silver stain, Dopa, tyrosinase and cholinesterase) were all negative. There was an intense positivity for the lisosomal enzymes (non specific sterases, and acid phosphatases). The ultrastructural study of the tumoral tissues as well as the cells of cultures showed abundant cells with tumoral aspects, with prominent nucleoli somewhat dilated granular endoplasmic reticulum, myelin-like figures, lipidic vacuoles and abundant lisosomes. No melanosomes or premelanosomes were observed. Beside these tumoral cells abundant typical fibroblastic elements were found. There was a great amount of collagen fibers with periodicity superior to the normal. The conclusion is that the desmoplastic melanoma must be considered as a tumor of mesenchimatous origin intervening in its development multiple local and general factors.
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PMID:[Desmoplastic melanoma]. 34 19

Human malignant melanocytes show characteristic morphologic modifications which are particularly evident in their specific organelles: melanosomes. These modifications are conserved in cell culture. The ultrastructural localization of tyrosinase, the enzyme which converts tyrosine and dopa into melanin, was determined in 13 human melanoma cell lines. The different cell lines possess 4 distribution patterns of melanin synthesis based on dopa oxidase activity. The two first pathways, which involve the Golgi apparatus, seem to differ by the amount of enzyme within this organelle. The third pathway mainly involves the smooth endoplasmic reticulum, whereas tyrosinase is visible only in vesicles in the fourth. Some cells synthesize the enzyme in the manner observed in very early embryos.
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PMID:Cellular localization of tyrosinase in human malignant melanoma cell lines. 40 30

During the course of applying electron microscopy to diagnostic surgical pathological specimens, three malignant tumors (malignant melanoma, fibrous mesothelioma, lymphoblastic lymphoma) were found to contain annulate lamellae, distinctive intracytoplasmic organelles composed of membrane stacks interrupted by constrictions or pores. In one case both annuli and lamellae were present, a combination rarely described in human tissue and in animal models. In this material, the annuli of the annulate lamellae were structurally similar to nuclear pores. It is postulated that the abundant fibrils are probably related to the unusual configuration of the annulate lamellae. A morphologic relationship of the annulate lamellae to both the endoplasmic reticulum (cases 1 and 2) and the nuclear membrane (case 3) supports the theory that annulate lamellae may be related to both of these structures.
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PMID:Annulate lamellae in human malignant tumors: report of three cases. 58 Aug 85

An ultrastructural dopa reaction, with glutaraldehyde--formaldehyde prefixation, was carried out on ten specimens of malignant melanoma showing a wide variation in melanosomal morphology. All tumours, but only a minority of tumour cells, contained reaction product. In all tumours the reaction product was distributed similarly in the Golgi apparatus and Golgi associated endoplasmic reticulum (GERL). However, differences were noted in its deposition in melanosomes. Whereas vacuolar and lamellar profiles sometimes contained reaction product, it was not seen in normal, granular and abortive melanosomes. Tumour cells without melanosomes were also seen to contain reaction product.
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PMID:Human malignant melanoma. Melanosomal polymorphism and the ultrastructural dopa reaction. 63 44

Scrotal skin of black Long-Evans rats and human thigh skin were maintained in vitro as organ cultures for as long as 14 days, and examined histologically using the combined skin splitting and Dopa techniques. Selected rat skin cultures received testosterone in the culture medium and/or were irradiated with ultraviolet light (290-320 nm UVL). With increased time in culture, scrotal melanocytes round up and there is an increase in epidermal pigmentation. Human skin behaves similarly; after eight days in vitro human melanocytes also become rounded, but remain strongly Dopa-positive. Addition of exogenous testosterone to cultured rat skin maintains dendritic morphology of melanocytes, but cell body size is still reduced. UVL irradiation stimulates melanocytes in rat skin cultures, maintaining their dendritic morphology and increasing epidermal and dermal pigmentation. Cultured skin receiving both UVL and testosterone illustrates a synergistic effect. Electron microscopic examination of cultured rat skin shows the presence of large melanosome complexes in keratinocytes, much larger than those found in vivo. Melanocytes appear to be active as they contain an extensive Golgi zone, rough endoplasmic reticulum, and melanosomes in various stages of formation. Dermis contained many dermal melanocytes and macrophages laden with melanosomes, correlating with the increased visible dermal pigmentation in vitro. This UVL stimulation of melanocytes in our skin organ cultures contrasts with the lack of melanogenic stimulation found in melanoma cell cultures. Our findings suggest that the intact epidermal melanin unit may be necessary for UVL stimulation of melanocytes.
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PMID:Organ culture of mammalian skin and the effects of ultraviolet light and testosterone on melanocyte morphology and function. 64 88

A null cell fraction was isolated from human peripheral blood by Ficoll density gradient centrifugation followed by removal of mononuclear phagocytes, passage through Ig-antiIg columns and sedimentation of E-rosette forming T cells. In contrast to the T cell fraction in the Null cell population exhibited cytotoxic activity against antibody-sensitized human melanoma target cells (ADCC reaction). This activity could be attributed to a low affinity Fc-receptor bearing cells present in the Null cell preparation. At the ultrastructural level in 2 h ADCC reaction most tumor cells were surrounded by up to 10 lymphoid cells which showed narrow junctions with parallel plasma membranes and local evaginations of lymphoid cells into recessus of the target melanoma cells. The mononuclear cell type found in close contact with the antibody-sensitized target cells had the following morphological criteria: 8 to 10 mu diameter, irregular nucleus, discrete rough endoplasmic reticulum, isolated ribosomes, cytoplasmic organelles concentrated under a ruffling membrane in the contact area with the tumor cell.
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PMID:Human peripheral Nullymphocytes: ultrastructural aspects of the "K" cell effect against a melanoma target cell. 73 73

Specific intracytoplasmic organelles, annulate lamellae and radial cisternae, have been studied in several human tumours. Annulate lamellae are observed in all cases of leiomyoma, leiomyosarcoma, rhabdomyosarcoma and malignant melanoma, whereas radial cisternae are only found in a case of leiomyosarcoma. Annulate lamellae are characterized by stacks of parallel arrayed long cisternae showing alternative arrangement of annuli and sacs. Some of these cisternae are connected directly with rough-surfaced endoplasmic reticulum and there is continuity with the lumen and membrane. Radial cisternae are mainly composed of two structures: numerous short cisternae, which are a variant of annulate lamellae, and numerous spherical particles derived from the cisternae. The cisternae are arranged parallel or radially around particles measuring up to 1100 A in diameter. These particles consisting of an amorphous high electron dense material without distinct limiting membrane are organized in groups and vary in number. There is no evidence of a direct relationship between these structures and viral infection.
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PMID:Fine structural study of annulate lamellae complexes in human tumors. 85 Oct 30

Electron microscopic investigations in 7 patients with different dermatoses or skin tumours containing amyloid showed that amyloid is synthesized in the cytoplasm of dermal cells. In 3 cases of localized primary amyloidosis of the skin highly active cells were demonstrated, showing grossly dilated cisternae of rough endoplasmic reticulum, resembling fibroblasts. Their intracellular product seemed amorphous, later filamentous, and was then released into the extracellular space. Extracellular aggregations of typical amyloid filaments were found partially surrounded by thin cytoplasmic remnants of the cells producing them. Subclinical amounts of amyloid found in porokeratosis of Mibelli, in superficial basal-cell carcinoma, in senile skin, and in clinically normal skin of a patient with malignant melanoma showed the same characteristics. Other cell types such as plasma cells and mast cells were well preserved and seemed stimulated; however, no amyloid precursors were found in their cytoplasm and no release was seen. We, therefore, conclude that dermal amyloid is generally produced by falsely programmed fibroblasts.
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PMID:Amyloid production by dermal fibroblasts. Electron microscopic studies on the origin of amyloid in various dermatoses and skin tumours. 91 78

Ultrastructural features of neoplastic cells can provide clues for correct diagnosis when light microscopy fails. Secretory granules are characteristic in the following tumors: mucin granules in poorly differentiated adenocarcinomas, zymogen granules in acinic cell carcinomas, lysosomal granules in prostatic carcinomas, melanin granules in malignant melanoma, carcinoid, islet cell tumors, pheochromocytoma, and neuroblastoma granules in the corresponding neoplasms. Among cytoplasmic organelles, rough surfaced endoplasmic reticulum characterizes adrenocortical, ovarian, and hepatocellular carcinomas and plasmacytomas. Tonofibrils are characteristic of squamous cell carcinomas. Glycogen deposits distinguish Ewing's sarcoma from lymphoreticular neoplasms. Intercellular relationships and membrane specialization are important features in the differential diagnosis of various undifferentiated tumors. The frequent resolution of difficult diagnostic problems by electron microscopy outweighs the disadvantages of this technique, such as the expense and time required.
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PMID:The usefulness of electron microscopy in the diagnosis of human tumors. 115 Feb 21


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