Xanthoma

KCAHTOMA, xanthoma (from Greek xanthos- yellow), a yellow tumor. The term K. is accepted to denote growths that have a yellow color and consist of so-called xanthoma cells (see below). In essence, the formations called K. are extremely diverse, and only some of them deserve to be classified as true tumors. In addition to the formation of tumors from xanthoma cells, there are very diverse cases in which, either in connection with a general disturbance of cholesterol metabolism or in connection with the local accumulation of cholesterol in the tissue, various cell types of macrophages, capturing small droplets of lipoids, turn into xanthoma cells. When this phenomenon is significant, one speaks of general or local xanthomatosis. Since 1910, since the works of Aschofi and his student Kammer, it has been customary to divide all such formations into three categories: 1) true K., 2) xanthelasmas, and 3) pseudoxanthomas. 1. True xanthomas (xanthome en tumeurs of the French), representing true tumors, are observed rarely. They develop, as a rule, under the skin, usually in such places as the area of the knee, elbow, heel, sacrum, and sometimes in other places of the body; they appear in the form of dense, lobular tumors ranging from pale yellow to brownish on section and on the surface; their volume can be different, but rarely exceeds the size of a chicken egg. Usually they are painful upon pressure. Often the tumors are fused with the joint capsule, tendon sheath, aponeurosis, or periosteum. Histologically it is discovered that the predominant element of the tumor is xanthoma cells, which represent cells containing a large amount of small droplets of lipoids in the protoplasm, most of which relate to doubly refracting light cholesterol esters. When these cells accumulate in significant quantities, the tissue acquires a yellow tint, whence the name. Xanthoma cells have the appearance of large cellular elements of rounded or polygonal shape with a small nucleus. When examined with a polarizing microscope, a large number of small doubly refracting light droplets and sometimes the smallest crystals are found in the protoplasm. These droplets give color reactions to lipoids, and in preparations that have come into contact with alcohol, due to the dissolution of lipoids, they have the appearance of small voids-vacuoles, which gives the protoplasm of these cells a foamy appearance ("foamy cells"). Xanthoma cells, in terms of their origin, represent diverse elements (reticuloendothelial system cells, macrophages of connective tissue, epithelium, endothelium of capillaries and lymph vessels, possibly fibroblasts); their transformation into xanthoma cells is associated with their adsorption of lipoids from surrounding juices (the so-called Speicherung of German authors). Xanthoma cells appear in the organism either in connection with a general saturation of the body's juices with cholesterol ester in general hypercholesterolemia, or in connection with tissue cholesterolophilia, or finally with the local formation of cholesterol esters in the tissue. These cells are distributed in groups, between which there are areas and layers of tissue of not always the same appearance, depending on which the tumors are given one or another name: in the so-called xanthofibromas this tissue has the character of mature connective tissue, in xanthosarcomas it corresponds to the structure of polymorphonuclear sarcoma. K. connected with tendons and aponeuroses often contain numerous giant cells, giving the tumor a resemblance to giant-cell sarcoma of the epulis type. The course of xanthomas is mostly benign; only in some cases of K. of the xanthosarcoma type did they give metastases. In recent times, there has been great doubt as to whether K. represent an independent form of tumor, and are not ordinary fibromas and sarcomas, the cells of which are successively transformed into xanthoma cells due to the deposition of cholesterol ester in them; the last assumption is supported by the works of a number of authors (Kirsch, Schmidt, Lu-barsch and others), who have found an increase in the amount of cholesterol in the blood (hypercholesterolemia) in such cases. As Lubarsch pointed out, the deposition of cholesterol in such tumors is favored by stagnation in the region of the tumor of lymph saturated with cholesterol. In connection with the above, it is proposed (Borst) not to denote these tumors with the term K., but to add the term "xanthomatodes" to the names "fibroma", "sarcoma". 2. Xanthelasmas, infiltrative xanthelasmas of Herxheimer, symptomatic K. of previous authors, appear in the form of yellow spots on the skin, sometimes flat (xanthoma planum), indistinguishable in consistency from the surrounding tissue and painless upon pressure; in other cases - slightly elevated or even nodular (xanthoma tuberosum), the size of a lentil to a bean, hard to the touch; often they are multiple; cases of xanthelasma, spread almost over the whole body, are designated as general xanthomatosis (xanthoma multiplex of previous authors). One of the frequent localizations of flat xanthelasma is the skin of the eyelids (xanthoma palpebrarum). The eruptive elements here are round or oval in shape, often have a linear arrangement and are surrounded by strongly pigmented skin. Xanthoma tuberosum mult. is encountered more rarely, which is located mainly on the extensor surface of the limbs, often symmetrically, in the form of nodules the size of a millet grain to a pea, round in shape, elastic in consistency. Xanthoma tuberosum multipl. is observed in middle age and only exceptionally in children. Histologically, in the areas of the above elements in the connective tissue of the skin, bundles and groups of xanthoma cells are found. Xanthelasmas have nothing in common with tumors, but represent the consequence of the deposition of cholesterol ester in the skin with the transformation of the local connective tissue cells capturing it into xanthoma cells (a relative granuloma reaction of xanthoma cells). Xanthelasmas are observed most often as secondary changes in all those diseases which are accompanied by an increase in cholesterol in the blood, i.e. hypercholesterolemia (see); these include diabetes, jaundice, some diseases of the liver and kidneys. Xanthelasmas are also observed in idiopathic hypercholesterolemias (in old age). In some cases, however, xanthelasmas appear without any hypercholesterolemia, and in such cases, which are often hereditary, one speaks of "xanthomatous diathesis", explaining it by tissue cholesterolophilia. The fact that xanthelasmas in most cases relate to manifestations of disturbed cholesterol metabolism is confirmed experimentally by Anichkov, Khalatov, Kuznetsovsky and others, who obtained xanthomatosis and xanthelasmas in animals by feeding them cholesterol. Besides cutaneous xanthelasma, xanthomatosis on the basis of disturbed lipoid metabolism can also manifest itself in the form of visceral xanthomatosis, which is detected in the form of universal deposition of lipoids in the elements of the reticuloendothelial system of internal organs, bone marrow, etc., with the transformation of these elements into xanthoma cells; these include such diseases related to each other as Niemann-Pick disease, Christian syndrome. 3. Pseudoxanthomas - resorptive xanthelasmas of Herxheimer - relate to the local formation of xanthoma cells where there is accumulation and resorption of lipoid masses; in these cases xanthoma cells are formed from local tissue cells phagocytizing and resorbing lipoids. The indicated pseudoxanthomatosis is a purely local change; it is detected very often in foci of various chronic inflammatory processes accompanied by fat decomposition of pus or dead tissue (chronic purulent cholecystitis, pyelonephritis, pyosalpingitis, appendicitis, mastitis, orchitis, actinomycosis, various protracted phlegmons, decomposing gummas, etc.), in destructive processes in adipose tissue (see Oleogranuloma), in necroses and decomposition of tumors. Being only a secondary change in another basic process, pseudoxanthomas have no independent significance. In general, in essence, pseudoxanthomas relate to what is called local xanthomatosis, and differ little from xanthelasmas; for this reason the name "pseudoxanthomas" must be recognized as much less successful than the terms "resorptive xanthelasmas" or local "resorptive xanthomatosis".

The article continues with a detailed classification of xanthomas, describing their histological features, clinical presentation, and the distinction between true tumors, xanthelasmas, and pseudoxanthomas. It emphasizes the role of cholesterol metabolism in their development and notes that while most are benign, some, like xanthosarcomas, can metastasize.

The text concludes by discussing the etiology of xanthomas, linking them to hypercholesterolemia and other metabolic disturbances. It also covers the experimental evidence supporting the role of cholesterol in the formation of these lesions and mentions specific diseases associated with xanthomatosis, such as Niemann-Pick disease.