Melanoma

Melanoma (synonym: malignant melanoma, melanoblastoma) - the tumor from melanoblasts - cells that produce pigment melanin. Melanoma develops on the background of previous nevus (see) either on an unmodified skin; on the mucous membrane, in the internal organs occurs very rarely.
Primary melanoma skin (brown, black, blue-purple, rarely light) has the form of a flat or protruding above the surface of education with thinned cover or ulceration, serous or dark discharge. Size from a few millimeters to several centimeters. Often around the base tumors observed purple Corolla Radiorama heavyweights in circumference is neoplastic infiltration of the skin; in later in the thickness of the skin in the nearest from the tumor areas appear blue dot plots satellites; the latter are a sign of disease progression or dissemination. Melanoma skin often spreads as in the regional lymph nodes or to distant organs in the blood vessels.
Clinical diagnosis difficult, determined with the help of research radioactive phosphorus, microscopic examination of fingerprints and separated from the surface of the wounded tumors. Biopsy is absolutely contraindicated because of the possibility of dissemination. The patient with suspected melanoma must be urgently directed to the doctor. The prognosis is unfavorable.
Treatment: surgery, radiotherapy, or a combination (only Oncology institutions).

Melanoma (from the Greek. melas, melanos - dark, black; synonym; melanostoma, melanoblastoma, melanocephalum, melanotaenia) - the tumor from melanoblasts (cells that produce the pigment melanin). In Russian literature the term melanoma apply, as a rule, in relation to a particular category of malignant tumors, but abroad it is customary to distinguish between two types of melanoma - benign and malignant. Given this kind of lack of terminological clarity, some authors prefer not to be limited by the term of melanoma, and specify what kind of melanoma they mean is benign or malignant.
Etiology, a pathogeny, a pathological anatomy. Until now the questions of etiology and pathogenesis of melanoma is a lot of uncertainty. The source of the tumor are melanoblasts - cells neuro-ectodermal origin arising from different sources: from the neural plate (melanoblasts epithelium of the retina), of ganglion scallops (melanoblasts choroid, meninges, the dermis). In most cases, melanoma occurs in the skin (70%), most often of lower limbs, neck, back, face, upper limbs, chest, a second! the most frequently takes the eye, then mucosa, soft meninges of the brain and spinal cord. As heterotopic melanoblasts are found in the tissues of the adrenal gland, colon, nose, throat, ear, throat, eye, liver, gallbladder, bile ducts, salivary glands, spleen, urethra, penis, peritoneum, the nerves. This may explain the relatively rare ectopic localization of melanomas in these bodies.
According to the concept of M. F. Glazunov, melanomas - vicious developed embryonic neuroectodermal part of the ectoderm. Neuroectodermal origin melanoblasts and the ability to produce insoluble polifenolami substances type b solutions, is chemically similar to adrenaline, allowed Masson (P. Masson) attributed M to the so-called cytokines melanogonus system. Look at nevus as a source of development of M very popular, but there are M and without any connection with birthmarks. Causes certain interest put forward by Gordon (M. Gordon) genetic concept of the emergence of M., particularly clearly demonstrated by him on the hybrid fish.
Cases of congenital melanoma have been described many times, but so far not solved the question of the origin of such M. allowed interplanetary transfer of the tumor. Predisposing moment for the growth of the tumor is considered an injury. Etiological link Meters with hormonal factors explain the benign course of the tumor before puberty, followed by a sharp malignancy or especially extensive metastasis of Feet during pregnancy.
Sometimes primary localization of melanoma cannot be set. This is because the primary tumor at the first metastases not only stops growing, but sometimes reverses its development, up to its complete disappearance.
Macroscopically M. skin and mucous membranes is represented in the form of a lump, pigmented to varying degrees, a soft consistence, easily izyaslau surfaces (printing. Fig. 3). A characteristic appearance of melanoma of the eye (see below Malignant melanoma of the eye).

melanoma of the intestine
Fig. 5. Multiple sites of melanoma in the gut

Developing in the membranes of the brain and spinal cord Feet swell, thicken, dense case surround the substance of the brain, infiltrating the subdural space and Dura. The color of these tumors dark brown or black. The preferential localization M bowel - rectum or small intestine. In the rectum melanoma is located in ampullar and has the shape of a polyp, sitting on the leg; polyp this soft consistence, easily ulcerated. In the small intestine tumor can be either single or multiple (printing. Fig. 5), in the latter case, it resembles in appearance polyposis. Painting polyps varies widely. In ectopic localization M not have a characteristic macroscopic picture and often non-pigmented (the so-called achromatic M).
Microscopic structure of melanoma are very variable. Basically there are two types of patterns. First: the tumor presents spindle-shaped cells, grouped in bunches, they intertwine. Among cells come across giant with large engines (one or more), with a large number of mitoses. Frequent hemorrhage and necrosis. Tumor stroma is, as a rule, entirely from vessels, separated by a thin argyrophyllum membranes. Morphological similarity of this tumor type sarcoma was the reason to call such melanoma "melanocarcinoma". If stroma highly developed (which are very rare), then we say about fibrolaryngoscopy. The second type microscopic structure M characterized by the abundance of cubic cells, oval or round shape with hyperchromic cores with multiple mitoses and giant multi-core cells containing bright eosinophilic cytoplasm. Sometimes these cells are branching fibers and have alveolar structure, sometimes on a structure reminiscent of the endocrine glands. The stroma is developed very poorly. Histologically melanoma similar patterns resemble cancer, which led to the term "melanocarcinoma". In some cases, when tumor cells form
trabeculae, and stroma is represented mainly by blood vessels that occur palisadoobrazny and halftone patterns resembling paraganglioma. In the Junior Meters you can find many kind of oval or stellate giant cells with acidophilus cytoplasm containing puzirkoviy kernel irregular shape. Masson describes the concentration of chromatin in the circle of nucleoli and education locatorobj figures in the kernel, which he believes is so specific to melanomas that serves to keep them in mind for differential diagnosis achromatic M
Often in the structure of malignant melanoma. combines elements of melanostoma and melanocarcinoma (so-called mixed tumors). The amount of melanin in tumor cells varies considerably. In some cases they are completely devoid of it - amalonaticus, or achromatic, M, while in others the number varies from a few brownish seeds to glycocoll mass black pigment, occupying all the cytoplasm of a cell. Regardless of the amount of melanin in tumor cells reaction with 3-4-dioksifenilalanina (DOP-reaction), identify bromelain in the cytoplasm, always positive; this means that the tumor cells do not lose their properties to produce melanin, although not always find it. The number of cells containing a pigment, varies not only in M different histological structure, but in different parts of the same tumor and in different metastatic nodes. Sometimes the cells themselves are represented achromatic, while the amount of melanin in the tumor stroma significantly (for example, when the skin melanoma).


For M is characterized by early and extensive metastasis, but sometimes the gap between education primary lesion and generalization of process reaches a dozen years.
Dimensions metastatic foci is inversely proportional to their number. When new metastases growth of old metastatic lesions may slow down or even stop. Metastases mg have, as a rule, lymph and blood, rarely implant character. Frequency localization of metastases in the first place are the regional lymph nodes, liver, lungs, skin, bones, a brain.
The consistency of metastatic nodes can be dense and soft. Dense nodes are usually dark brown or black in color (often in the liver); soft - lighter, spotted, sometimes white. Histologically metastases may be the type of melanostoma or melanocarcinoma, often mixed.
Histological diagnosis M, containing large amounts of pigment, is usually not difficult; when achromatic melanoma requires differential diagnosis. Distinctive features of M are: radiance the location of chromatin in nuclei; high activity of tyrosinase in cells Meters, determines the degree of evil - the quality of the tumor, the tumor cells oxidase, which the chromatin produced by melanoblasts, turns into melanin. Less permanent sign is yellow fluorescence of tumor cells in the study using a fluorescent microscope. Diagnostic and prognostic value can have proliferative cell response in the area of growth of the primary lesion, the intensity of which can sometimes parallel extent of his zlokacestvennoe.
Below is a description of the clinical picture of the two most common types of malignant melanoma: a malignant M. the skin and eyes. For a description of other types of M - see the articles on the individual organs.