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Keratoacanthoma

Keratoacanthoma — quickly growing benign epidermal tumor of hair follicles which is localized mainly on open parts of a body and extremities, especially on extensor surfaces.
Keratoacanthomas of unusual localization — hyponychial, on mucous membranes of lips, cheeks, a hard palate, a conjunctiva, a nose are described.

Epidemiology

Elderly people are ill a keratoacanthoma mainly. More young than 20 years the disease almost does not occur at persons. Men are ill twice more often than women.

Classification

According to the WHO classification allocate the following options of a keratoacanthoma:
• solitary;
• huge;
• a keratoacanthoma with peripheral growth;
• hyponychial;
• multiple in combination with immunosuppression and a syndrome of Torre;
• multiple eruptive (the multiple self-beginning to live elements at children and teenagers).

Etiology and pathogeny

The etiology is unknown. A certain significance is attached to a virus factor. Virus particles at the ultrastructural level and existence of DNA of a virus of papilloma of the person of the 25th type are found almost in half of cases of a solitary keratoacanthoma. The last option meets most often, multiple elements are less often observed.
The generalized keratoacanthoma often has family character, autosomal is inherited it is prepotent.
The multiple keratoacanthoma can be manifestation of a paraneoplasia at novobrazovaniye of internals, especially a gastrointestinal tract.
It is taken for granted that the keratoacanthoma arises from a giperplazirovanny epithelium of a funnel of one or several, close located hair follicles and the related sebaceous glands.

Clinical signs and symptoms


Education has an appearance of a roundish or oval exophytic node on the wide basis reddish, sometimes with a cyanotic shade of color or color of normal skin, with a diameter of 2 — 3 cm and more. The central part of a tumor is filled with horn masses, the regional zone is raised in the form of the high roller.
After a phase of active growth there can come the phase of stabilization during which the tumor does not change in sizes. Then in 6 — 9 months there can come spontaneous regression with disappearance of a tumoral node and formation of an atrophic hem. In certain cases the phase of stabilization does not come, and the tumor can reach the huge sizes — to 10 — 20 cm in the diameter.
The multiple keratoacanthoma can be shown or in the form of consistently arising small knots, or in the form of several centers arising at the same time. At the first option elements appear gradually on various sites of an integument, but is especially frequent on a face and extremities. They are provided by papules and nodes with the retraction in the center filled with the horn masses which is allowed within several months with formation of an atrophic hem. At the second option the set of large follicular papules with a diameter of 2 — 3 mm at the same time appears.

The diagnosis and the recommended clinical trials

The diagnosis is made on the basis of clinical manifestations; at solitary or multiple defeats carry out an ekstsizionny biopsy, at large elements — a diagnostic biopsy of a zone of the roller.
On the basis of results of pathomorphologic research distinguish 3 stages of a keratoacanthoma:
• in the I stage (a stage And) the deepening in epidermis filled with horn masses is observed. In lateral departments horn masses is surrounded an epidermis duplikatu-swarm in the form of "collar". The epidermal tyazh in the subject derma containing cells with hyperchromic kernels depart from the basis of a keratotichesky stopper. Zone of a basal membrane of a sokhrann;
• in the II stage (a stage In) in the basis of a crater sharply expressed epithelial hyperplasia with penetration ploskoepitelialny tyazhy deeply in a derma comes to light. Cells of a rostkovy layer are, as a rule, faintly painted, is larger, than normal, mitoses and the phenomena of a dyskeratosis are sometimes visible. In epidermal outgrowths signs of atypia of cells, polymorphism, their lower bound not everywhere accurate find. In a derma hypostasis, inflammatory reaction of polymorphic type decide on lymphocytes, neutrophylic, eosinophilic granulocytes with impurity of plasmocytes. Infiltrate cells sometimes get into epidermal outgrowths. The similar picture can be considered as a precancer;
• in the III stage (the stage C) is observed disturbance of integrity of a basal membrane with growth of epidermal outgrowths deep into of a derma and an otshnurovka of complexes of ploskoepitelialny cells. Polymorphism and a hyperchromatosis of kernels increase, the dyskeratosis is replaced by pathological keratinization with formation of "horn pearls", i.e. all symptoms of planocellular cancer with keratinization appear. In the basis of the center dense inflammatory infiltrate comes to light.
In cases of regression of a keratoacanthoma, possible in the I—II station, the horn stopper decreases, the structure of a basal layer is normalized, proliferation of epidermis stops. In infiltrate a large number of fibroblasts with the subsequent fibroplasia and forming of a hem appears.
Histologic changes at a multiple keratoacanthoma same as at solitary, however proliferation and atypia are less expressed and communication with an epithelium of mouths of hair follicles is more accurately traced.

Differential diagnosis

The high-differentiated planocellular carcinoma cutaneum, usual warts, a huge contagious mollusk, an actinic keratosis, a skin horn, a bazaliom. The multiple form of a keratoacanthoma should be differentiated with Kirle's illness.

General principles of treatment of keratoacanthomas

At solitary small elements make their electroexcision, surgical excision, laser evaporation, a cryolysis.
At solitary large elements surgical excision is shown.
At the multiple centers and for prevention of an ozlokachestvleniye of educations carry out therapy by synthetic retinoids:
Atsitretin in 50 — 75 mg 1 r / days, 4 — 11 weeks.

Forecast

The keratoacanthoma — a new growth, is characterized by fast development and often spontaneous regressing (usually in 2 — 6 months). Transformation in planocellular cancer is in some cases possible.
 
"Osler's disease   Skin horn"