113. Malignant epithelial and mesenchymal skin tumors: origin, terminology, types. Origin, terminology, types. Macro-microscopic structure, complications, clinical significance.

A malignant tumor that develops from poorly or undifferentiated epithelial cells is called "cancer". The tumor usually has the appearance of a node of a soft or dense consistency, its boundaries are indistinct, sometimes merge with the surrounding tissue. A cloudy liquid, cancer juice, is scraped off the whitish surface of the incision of the tumor. Cancer of the mucous membranes and skin ulcerates early.

Histological forms of cancer:

– "cancer in situ" (carcinoma in situ);

– squamous cell (epidermal) cancer with and without keratinization;

– adenocarcinoma (glandular cancer);

– mucosal (colloidal) cancer;

– solid (trabecular) cancer;

– small cell carcinoma;

– fibrous cancer (scirr);

– medullary (adenogenic) cancer

Squamous cell (epidermal) cancer develops in the skin and mucous membranes covered with a flat or transitional epithelium: in the oral cavity, esophagus, cervix, vagina. In mucous membranes covered with prismatic epithelium, squamous cell carcinoma develops only after previous epithelial metaplasia. The tumor consists of strands of atypical epithelial cells growing into the underlying tissue, destroying it and forming nest clusters in it. Tumor cells can retain the ability to keratinize, then formations resembling pearls appear — cancerous pearls. With a lower degree of cell differentiation, keratinization does not occur. In this regard, squamous cell carcinoma can be keratinizing and non-keratinizing. Adenocarcinoma (glandular cancer) develops from the prismatic epithelium of the mucous membranes and the epithelium of the glands. It is found in mucous membranes and glandular organs. This adenogenic tumor has a structure similar to an adenoma, but unlike it, atypism of epithelial cells is noted in adenocarcinoma: they are of different shapes, the nuclei are hyperchromic. Tumor cells form a glandular formation that grows into the surrounding tissue, destroying it, while it loses the basement membrane. There are the following variants of adenocarcinoma:

– acinar — predominance of acinar structures in the tumor;

– tubular — the predominance of tubular formations;

– papillary — represented by atypical papillary growths. Adenocarcinoma has a different degree of differentiation.

Mucous (colloidal) cancer is an adenogenic carcinoma, the cells of which have signs of morphological and functional atypism, a perverted mucus formation. Cancer cells produce a lot of mucus and die in it. The tumor has the appearance of a mucous, or colloidal, mass,

in which atypical cells are found. Mucous (colloidal) cancer is a form of undifferentiated cancer.

Solid (trabecular) cancer (from Latin. solidus —single, dense) is a form of undifferentiated cancer with pronounced atypism. Cancer cells are arranged in the form of trabeculae (trabecular cancer), separated by layers of connective tissue. Mitosis is quite common in tumor cells. Solid cancer grows quickly and metastasizes early. Small cell carcinoma is a form of undifferentiated cancer that consists of monomorphic lymphocyte—like cells that do not form any structures; the stroma is extremely scarce. There are many mitoses in the tumor, necrotic changes are frequent. Growth is rapid, metastases occur early. Sometimes it is not possible to establish the histogenesis of a tumor — unclassifiable cancer.

Fibrous cancer, or scirr (from the Greek scirros — dense), is a form of undifferentiated cancer with extremely atypical hyperchromic cells located among layers and strands of coarse—fibrous connective tissue. The main feature of this form of cancer is the obvious predominance of stroma over parenchyma. The tumor is characterized by high malignancy, early metastases often occur.

Medullary (adenogenic) cancer is a form of undifferentiated cancer, its main feature is the predominance of parenchyma over stroma, which is very small. The tumor is soft, white-pink in color, resembles brain tissue (cerebellar cancer). It consists of layers of atypical epithelial cells, contains many mitoses, grows rapidly and necrotizes early, gives early and multiple metastases.

Mixed forms of cancer consist of the beginnings of a flat and cylindrical epithelium — dimorphic cancers.