Vegetative follicular dyskeratosis: causes, symptoms, diagnosis, treatment

Vegetative follicular dyskeratosis (syn. Darier's disease) is a dermatosis inherited in an autosomal dominant pattern. Three clinical varieties have been described: classical; localized (linear or zosteriform); warty dyskeratoma. Clinical manifestations of the disease occur in childhood, the process takes a chronic course with a tendency to progress. The rash is usually localized on seborrheic areas of the skin of the chest, back, scalp, behind the ear, but can spread to the skin of the extremities, face, affect the mucous membrane of the oral cavity. Keratotic follicular papules of normal skin color or yellowish-brown, covered with small crusts are characteristic; warty papules with weeping phenomena are also encountered. There may be vesicular-bullous rashes, changes in the nail plates, palmar-plantar punctate keratoses, a combination with bone cysts have been described. On the back of the hands, rashes resembling common warts are often found, most likely corresponding to the classic picture of Hopf's acrokeratosis. Often, the dermatosis is complicated by a secondary infection.

Pathomorphology of vegetative follicular dyskeratosis. Darier's disease is characterized by suprabasal acantholysis with the formation of slits containing acantholytic cells and proliferation of dermal papillae protruding into the bladder cavity. Dyskeratosis is most often detected in areas of crack formation in the form of "round bodies" in the granular layer and grains in the horny layer. Round bodies are epithelial cells of a rounded shape, not connected with the surrounding cells, having a basophilic homogeneous cytoplasm, a pycnotic nucleus and a light rim along the periphery. Grains are homogeneous eosinophilic formations with barely noticeable nuclei or without them. In the epidermis, hyperorthokeratosis with the formation of horny plugs in the mouths of hair follicles, acanthosis, papillomatosis are noted. In the dermis - perivascular lymphohistiocytic infiltrate with single eosinophilic granulocytes.

According to electron microscopic examination, round bodies are large cells with a wide band of vacuoles around the nucleus and organelles along the cell periphery. Acantholytic cells have a similar structure. Vacuolization of the cytoplasm increases as the cells move toward the surface of the epidermis; in the granular layer, tonofilaments and associated keratohyalin granules are pushed toward the cell membrane; lamellar granules predominate among the organelles. The granules contain fine-grained and thin-fibrous structures diffusely located in the cytoplasm; the nucleus is absent. Lysed epithelial cells are found in the upper layers of the epidermis, probably representing the final stage of the existence of round bodies. Atypical desmosomes are found in the acantholysis zone. In these desmosomes, the middle layer is absent or cleared, unevenly contrasted, as if eaten away.

Histogenesis of vegetative follicular dyskeratosis. According to electron microscopic examination, the main processes occurring in the epidermis are characterized by vacuolization of individual epithelial cells, progressing as the cells move toward the surface of the epidermis and condensation of tonofilaments in them. The latter are associated with large keratohyaline granules, already noticeable in the spinous layer. IB Caulfield called this process premature keratinization. It was previously assumed that grains are the final stage of differentiation of round bodies, however, since grains do not contain keratin, they are probably formed independently of round bodies. The basis of acantholysis in Darier's disease is considered to be the formation of defective desmosomes, loss of contacts of tonofilaments with desmosomes and a defect in the intercellular cementing substance.

Other factors are also important in the pathogenesis of Darier's disease: decreased cellular immunity, activity of some enzymes (NADP-dependent and G-6-PDP,) involved in the keratinization process. Vitamin A deficiency is believed to play an important role, indirect evidence of which may be successful treatment of the disease with aromatic retinoids and vitamin A.

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