DISCANT

DISCANT, see Voice. DISKERATOSIS, dyskeratosis, a term introduced into dermatological literature by Darier to denote distinctive changes in the epidermis, consisting mainly in that a certain number of cells of the Malpighian network undergo significant morphological changes, at which time individual cells often lose the fibers connecting them to neighboring cells,-so-called desmolysis occurs; the cells thereby fall out of the general connection, become discomplexed, and as free elements are easily found in all layers of the epidermis, up to the horny. In D. the cells are arranged disorderly, large round cells with sharply limited and well-staining nuclei, basophilic granular protoplasm, and double-contoured, strongly light-refracting shell,-so-called round bodies ('corps ronds'). Further, oval and round acidophilic bodies are found, which either have no nuclei at all or have only remnants of them, the so-called grains ('grains'). The latter formations are apparently the product of transformation of the round bodies. In addition, in D. attention is drawn to the large number of abnormal mitoses and the variously abnormal shape of the nuclei of epithelial cells; the nuclei are either small or very large, often fragmented (leukocyte-like) and multiple (so-called epithelial giant cells). Thus, in D. the normal physiological process of keratinization is grossly violated, a peculiar degeneration of the cells of the Malpighian network occurs, their dyskeratinization. D. apparently proceeds completely independently from another type of disorder of keratinization-parakeratosis. Phenomena of D. are encountered in various skin diseases; they have been found in various forms of skin cancer, in spinocellular epitheliomas (dyskeratotic cells were described under the name of pseudococcidia), in warts, in blastomycosis, in actinic dermatitis in particularly predisposed subjects, etc. But dyskeratotic changes are especially characteristic and predominant in four skin diseases: 1) in Darier's disease (see Darier disease), 2) in Paget's disease, 3) in molluscum contagiosum and 4) in Bowen's disease. These dermatoses, выделенные by Darier into a separate group of D., have nothing in common with each other either clinically or etiologically (with the possible exception of Paget's and Bowen's diseases), they are united only by the presence of significant dyskeratotic changes; it should be noted that this grouping of dermatoses according to purely morphological criteria meets objections (Pautrier, Levy, Diss and Masson), all the more so that, as indicated above, D., although to a lesser degree, is also encountered in other skin diseases. In the last decade, the old dispute (Ribbert) about the origin of dyskeratotic cells characteristic of Paget's disease (so-called Paget cells) has revived. Masson, Pautrier and others see in them true cancer cells that have immigrated into the epidermis from the underlying, deeper necrotic foci; this school of Masson excludes Paget's disease from the group of dyskeratoses and precancerous conditions, considering it an epidermotropic cancer. Recently, some authors see a true epithelioma (of the intraepidermal type) also in another dyskeratosis-Bowen's disease. Bowen's disease (syn.: dermatose prйcancer-cereuse de Bowen, dyskeratosis lenticulaire et en disques), first described by him in 1912, represents a peculiar chronic progressive precancerous condition of the skin. As for its etiology, only hypotheses exist: nevus-like, toxic, infectious-toxic, etc.; a number of authors consider Bowen's disease as a dermatosis of the naevus type (cases of the development of Bowen's disease from maternal spots have been observed). Bowen's disease is relatively rare and affects persons of both sexes between the ages of 20 and 70 years.-The patho-anatomical picture is always characteristic due to significant dyskeratotic changes. The epidermis is thickened, there is always a sharp boundary between the epidermis and the dermis. The Malpighian layer consists of disordered vacuolated cells of the most diverse size, shape and color; changes in the nuclei are especially striking (see above; so-called Bowen's clumping), a significant number of figures of normal and amitotic division. At the same time, cells characteristic of another D.-Darier's disease-may be present-'round bodies', 'grains', etc. In the proper skin around the dilated vessels, infiltration of lymphocytes, leukocytes and plasma cells.-The pathogenesis is not clarified. The fact of the extraordinary similarity of histological changes in Bowen's disease with the changes obtained experimentally in animals by smearing the skin with components of tar (in the stage preceding the formation of cancer) deserves attention. Bowen's disease often ends with the transition to true cancer.-The clinical picture is extremely diverse. There is no favorite localization. Mucous membranes are rarely affected. The disease proceeds either in the form of asymmetric brownish-red, scaling or crusted, sometimes verrucous, little infiltrated papules, which usually group together and then merge into plaques of various shapes or in the form of multiple, scattered, sharply limited, almost non-infiltrated light brown or brown-red, the size of a lentil and larger, scaling spots, often resembling psoriasis or seborrheic eczema [see separate table (Vol. VIII, art. 739-740, Table 2), Fig. 1]. At the sites of regressed eruptions, atrophy often remains. Sometimes papular and spotted eruptions occur simultaneously, and often the transition of spots into papules is noted. Martinotti distinguishes the spotted, papuloid, nodular and neoplastic phases of Bowen's disease. Subjective phenomena are absent. In addition, Bowen's disease can proceed in the most diverse forms, for example in the form of a single hyperkeratotic formation (Gruitz), dense eroded thickening (M. Jessner), leukoplakia (Szathmary), etc. The discs of Bowen's disease often subsequently partially grow tumor-like and ulcerate; such areas sometimes turn out to be already a true carcinoma.-The course is chronic. No changes are found in internal organs.-Diagnosis is difficult. In differential diagnosis, one should keep in mind psoriasis, seborrheic eczema, senile keratoses, naevus, Darier's disease, tertiary syphilids, etc. Histological research is always required to distinguish Bowen's disease from the so-called epithelioma pagetoides (a very benign superficial basal cell epithelioma), in which dyskeratotic changes are absent. Extramammary and extragenital cases of Paget's disease should hardly be distinguished from Bowen's disease. Cases of Queyrat's erythroplasia (epitheliome papillaire nue, first described in 1893 by Fournier and Darier)-is apparently nothing other than Bowen's disease of mucous and semi-mucous membranes.-The prognosis in widespread cases is poor, since Bowen's disease is a precancerous condition. The best and almost only reliable method of treatment is radical surgical removal of the foci of the disease; some have seen improvement from X-rays and radium.