Keratoakantoma: causes, symptoms, diagnosis, treatment

Keratoakantoma (syn: molluscum pseudocarcinomatosum, molluscum sebaceum, tumor-like keratosis) is a rapidly growing benign tumor in the development of which the importance of viral infection, immune disorders, long-term effects of various unfavorable, mainly exogenous factors (trauma, ionizing radiation, mineral oils, tar , insolation, etc.).

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Causes of keratoacanthoma

According to G. Burg (2000), virus particles detected at the ultrastructural level and the presence of human papillomavirus DNA of the 25th type are found in almost half of the cases of solitary keratoacanthoma. The latter variant is most often encountered, and fewer elements are observed less often.

Multiple keratoacanthomas are often family-specific, inherited autosomal dominant, may be a manifestation of paraneoplasia in cancer of internal organs, especially the digestive tract (Torre syndrome).

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Histogenesis

The histological pattern is similar to that of solitary keratoacanthoma, but the proliferative process and atypia are less pronounced, and a link to the epithelium of the mouths of the hair follicles can be traced.

It is believed that keratoacanthoma originates from the perforated epithelium of the funnel of one or more closely related hair follicles and associated sebaceous glands.

Symptoms of keratoacanthoma

Typical localization of the tumor on the open parts of the body and limbs, especially on the extensor surfaces, mainly in the elderly. The tumor has the appearance of a rounded or oval exophytic node on a broad base, reddish, sometimes with a cyanotic shade of color or normal skin color, with a diameter of 2-3 cm or more. The central part of the tumor is filled with horny masses, the marginal zone in the form of a high roller. After the active growth phase, the stabilization phase usually occurs, during which the tumor does not change in size, then after 6-9 months - the phase of spontaneous regression with the disappearance of the tumor node and the formation of an atrophic scar. In some cases, the stabilization phase does not occur and the tumor can reach gigantic dimensions - up to 10-20 cm in diameter - and transform into squamous cell carcinoma. Also described are keratoacanthomas of unusual localization - subungual, on the mucous membranes of the lips, cheeks, firm palate, conjunctiva, nose.

In the development of keratoacanthoma, three stages are distinguished, having a characteristic histological picture. In stage I (stage A), a deepening in the epidermis is observed, filled with horny masses. In the lateral sections of the horny masses are surrounded by a duplicate of the epidermis in the form of a "collar". From the base of the keratotic plug, the epidermal cords extend into the underlying dermis, containing cells with hyperchromic nuclei. The basal membrane zone is preserved. In stage II (stage B), sharply expressed epithelial hyperplasia is revealed at the base of the crater, as a result of which epithelial outgrowths penetrate deeply into the dermis. Cells of the Malpighian layer are usually pale, larger than normal, sometimes mitosis and dyskeratosis are seen. In the epidermal processes, signs of atypia of cells, polymorphism, the lower border of them are not always clear. In the dermis - edema, an inflammatory reaction with infiltration of lymphocytes, neutrophilic and eosinophilic granulocytes with an admixture of plasmocytes. Cells of the infiltrate sometimes penetrate into the epidermal outgrowths. A similar picture can be considered as nredrak. In stage III (stage C), there is a violation of the integrity of the banal membrane with the growth of epidermal outgrowths into the interior of the dermis and the phenomena of lacing the complexes of flat epithelial cells. Polymorphism and hyperchromatosis increase, dyskeratosis is replaced by pathological cornification with the formation of "horny pearls", all signs of flat cell cancer with keratinization appear. At the base of the focus is a dense inflammatory infiltrate.

With regression of keratoacanthoma, possible in I-II stages. Horny cork decreases, the structure of the basal layer is normalized, signs of hyperproliferation of the epidermis disappear, and a large number of fibroblasts with final scar formation appear in the infiltrate.

Multiple keratoacanthoma can be observed both in the form of successively appearing nodules, and in the fork of simultaneously occurring several foci. With the nerve option, the elements appear gradually in different areas of the skin, but especially on the face and limbs. They are represented by papules and nodes with a westernization in the center. Filled with horny masses, resolved for several months with the formation of atrophic scars. At the second variant simultaneously appears a lot of large follicular papules with a diameter of 2-3 mm.

Diagnosis of keratoacanthoma

Differentiate keratoacanthoma from the initial stage of squamous cell carcinoma. The presence of a crater-like (mollusciform) structure in keratoacanthoma and the absence of atypia of nuclei are considered to be the most important differential diagnostic features. From molluscum contagiosum differs absence of mollusc bodies.

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