Acanthosis Nigricans

ACANTHOSIS NIGRICANS (from Greek akantha - thorn and Latin niger - black), a papillary-pigmentary dystrophy of the skin, a rare dermatosis which in severe, progressive form is observed in old age and in many cases is associated with malignant neoplasms of internal organs. The benign, or juvenile form, occurring in children, may last for decades without affecting the general condition. Symptoms: 1) formation of papillary proliferations, 2) limited or diffuse pigmentation and sometimes hyperkeratosis. Localization is usually symmetrical: neck, nape, face, axillary regions, chest, area around the navel, genital parts, anus, lumbar region, elbow and knee bends, backs of hands and feet; sometimes conjunctiva, mucous membranes of lips, mouth, and vagina. The disease begins with the appearance of abnormal yellowish, gradually darkening skin discoloration. In the developed picture of the disease, the skin is moderately thickened, rough, dry, sometimes peeling, colored in dark shades of various colors (up to black), covered with papillary elevations, which, arranged in close rows, give the skin a lichenified appearance. - The path-anatomical picture of this rare disease is characterized, mainly, by pigmentary and papillary dystrophy (see) of the skin, which was designated by Pollitzer in 1890 as A. p. The skin changes observed in this disease are, on the one hand, the enhanced symmetrical deposition of slate-black pigment in the skin, and on the other hand, a change in the relief of the skin, acquiring a grainy appearance of shagreen or divided by intersecting lines into polygonal plates. In more pronounced cases, the skin is covered with papillary growths in the form of pointed condylomas or hanging mollusks. Pigmentary dystrophy never extends to the mucous membranes, while papillomatosis affects both the skin in the areas mentioned above and the mucous membranes covered with stratified squamous epithelium (mucous membrane of the tongue, gums, cheeks, pharynx, esophagus and sometimes vagina). Histological changes in the skin consist in an increase in the horny layer, phenomena of acanthosis (see) and proliferation of papillae. In addition, the appearance of grains of black-brown, iron-free pigment in the Malpighian layer is noted. Initially, histologically only an increase in the granular and Malpighian layers is found, then proliferation of the papillary layer occurs, leading to the appearance of true papillary formations. In the subepithelial layer, in addition to the presence of pigment-containing cells, many mast cells are noted. - The pathogenesis of A. p. has been little studied to date. The mycotic theory of the origin of A. p. by Pollitzer has been rejected by all researchers. The assumption of Hallopeau that in A. p. there is a carcinomatosis of the skin has not received support. In view of the fact that most patients with A. p. suffer from cancer of internal organs (63%), the skin disease was attributed to cancerous cachexia or cancerous toxiderma (Couillaud, Unna). The only confirmation of the latter is the case of Spietschka, in which A. p. ended in clinical recovery after the removal of a decidualoma of the uterus. Darier's theory, which first established the pathogenesis of A. p. as depending on the lesion of the solar plexus and adrenal glands by cancer, had many supporters at one time, but now it is abandoned. Recently, in connection with the publication of relevant cases (Buri, Filser, Miescher-Guido), the transmission of the disease is considered hereditary; thus, in the pathogenesis of A. p., the constitutional factor must be recognized. Bogrov definitely points out that in 50% of cases in patients, long before the onset of the disease, various disorders of pigmentation and relief of the skin (birthmarks, warts) are noted. - The prognosis depends on the underlying process. A. p. may remit and even disappear after surgical removal. In general, the disease is incurable. - Treatment is hygienic-dietetic and symptomatic.