Squamous cell skin cancer

Squamous cell skin cancer (synonym: spinocellular cancer, squamous cell epithelioma, spinalioma) is an invasive tumor with squamous cell differentiation. It can occur in any part of the body, but open areas exposed to sunlight are especially often affected; in addition, it often occurs on the lower lip. Squamous cell carcinoma also occurs on the external genitalia and in the perianal area. It is the most malignant tumor of all epithelial skin neoplasms.

Squamous cell skin cancer occurs predominantly in elderly people, equally often in men and women.

According to scientific literature, squamous cell skin cancer often occurs against the background of pathological changes in the skin: precancerous diseases, for example, precancerous cheilitis of Manganotti), focal cicatricial atrophy, on scars after burns, injuries. The WHO classification (1996) indicates the following types of squamous cell carcinoma: spindle cell, acantholytic, warty with the formation of a cutaneous horn, lymphoepithelial.

A distinction is made between squamous cell skin cancer, which develops against the background of actinic keratosis, and squamous cell skin cancer, which occurs in scar tissue, at the site of burns, mechanical damage or chronic inflammation (lupus tuberculosis of the skin, late X-ray dermatitis, etc.). These differences are based mainly on the tumor's tendency to megastasis.

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What causes squamous cell skin cancer?

Squamous cell skin cancer may develop against the background of actinic keratosis, post-burn scar tissue, in places of constant mechanical damage, chronic inflammatory dermatosis such as hypertrophic lichen planus, tuberculous lupus, X-ray dermatitis, pigment xeroderma, etc. Squamous cell carcinoma developing on sun-damaged skin, in particular, foci of actinic keratosis, metastasizes rarely (0.5%), while the frequency of metastasis of squamous cell carcinoma occurring on scars is more than 30%, and in foci of late X-ray dermatitis - approximately 20%.

Histopathology and pathomorphology of squamous cell carcinoma of the skin

Histologically, a distinction is made between keratinizing and nonkeratinizing forms of squamous cell carcinoma. In the keratinizing form, there is a proliferation of epithelial cords, expressed by polymorphism, discomplexation and dyskeratosis of individual cells ("horny pearls").

A distinction is made between keratinizing and nonkeratinizing squamous cell carcinoma. In both forms, the tumor consists of randomly located complexes of atypical squamous epithelial cells with invasive growth into the deeper layers of the dermis and subcutaneous tissues. The degree of cellular atypia may vary and is characterized by a change in the size and shape of the cells themselves, their nuclei, a change in the nuclear-cytoplasmic ratio, the presence of polyploid forms, and pathological mitoses. Cell differentiation occurs with phenomena of excessive keratinization, which is accompanied by the appearance of so-called horny pearls - foci of hyperkeratosis of a rounded shape with signs of incomplete keratinization in the center, few or no keratohyalin granules.

In nonkeratinizing squamous cell carcinoma, strands of epithelial cells with pronounced polymorphism are found, the boundaries of which are difficult to determine. The cells have different shapes and sizes and small hyperchromatic nuclei. Pale nuclei-shadows and nuclei in a state of decay are encountered. Mitoses are often detected, usually pathological.

A. Broders (1932) established four degrees of malignancy of squamous cell carcinoma depending on the ratio of mature (differentiated) and immature cells in the tumor, as well as the degree of their atypia and the depth of invasion.

At the first stage, the cell cords penetrate into the dermis to the level of sweat glands. The basal layer in places shows signs of disorganization, is not clearly separated from the surrounding stroma. Differentiated squamous epithelial cells with well-developed intercellular bridges predominate in the tumor cords, some of them with signs of atypia. There are quite a lot of "horny pearls", some of them in the center with a completed keratinization process, in the dermis around the tumor there is a significant inflammatory reaction.

The second degree of malignancy is characterized by a decrease in the number of differentiated cells, there are few “horny pearls”, the keratinization process in them is not complete, and there are quite a lot of atypical cells with hyperchromic nuclei.

At stage III, the keratinization process is almost completely absent, keratinization is observed only in individual groups of cells with weakly eosinophilic cytoplasm. Most tumor cells are atypical, there are many mitoses.

For the IV degree of malignancy, there is a complete absence of signs of keratinization, almost all tumor cells are atypical without intercellular bridges. The inflammatory reaction in the stroma is very weak or absent altogether. To distinguish such an undifferentiated, anaplastic tumor from melanoma or sarcoma, it is necessary to use a panel of monoclonal antibodies, including cytokeratins, S-100, HMB-45 and lymphocytic (LCA) cell markers.

The study of the inflammatory infiltrate in squamous cell carcinoma using histological, histochemical and immunological methods showed that T-lymphocytes, natural killers, macrophages and tissue basophils are found in growing and metastasizing tumors, the degranulation of which is observed both in the tumor itself and in the stroma.

In addition to the above-described forms of squamous cell skin cancer, the following histological types are distinguished: acanthotic, bowenoid, spindle cell. The acanthotic type (syn.: carcinoma spinocellulare segregans, pseudoglandulare spinalioma) develops more often in elderly people due to actinic keratosis. Histological examination of this type shows that tumor complexes and cords undergo destruction, transforming into tubular and pseudoalveolar structures lined with one or more rows of atypical cells; keratinization is not always observed. Sometimes acantholytic or dyskeratotic cells are found in such cavities.

Bowenoid type of squamous cell carcinoma is characterized by pronounced polymorphism of nuclei and absence of "horny pearls" in tumor cords. Dyskeratosis and poikilocytosis are sharply expressed.

The spindle cell type of squamous cell carcinoma is characterized by the presence of structures consisting of spindle cell elements, may resemble sarcoma, does not have clear histological signs of keratinization, has a more pronounced infiltrating growth, more often recurs and metastasizes, and has a less favorable prognosis. However, using electron microscopy, the epithelial origin of this type of cancer has been proven based on the detection of tonofilaments and desmosomes in cancer cells.

Histogenesis of squamous cell carcinoma of the skin

Proliferation and lack of differentiation of epithelial elements in squamous cell carcinoma occur as a result of tissue regulation disorder and malignant autonomy of their functions. The importance of the immune system state of antitumor surveillance for the occurrence and development of the tumor process, in particular squamous cell carcinoma, is clearly demonstrated by the fact that the frequency of basal cell and squamous cell carcinoma is 500 times higher in patients with transplanted organs who received immunosuppressive therapy compared to populations of people of a similar age group. In the pathogenetic plan, in addition to immunosuppression, a clear correlation was revealed between the occurrence of squamous cell carcinoma, the actinic factor and the oncogenic cofactor of the impact of human papillomavirus types 16 and 18.

Symptoms of squamous cell skin cancer

Clinically, squamous cell skin cancer is usually a solitary node, but can also be multiple. Exo- and endophytic growth forms are distinguished. In the exophytic form, the tumor node rises "above the skin level, has a wide base, dense consistency, is slightly mobile, and is often covered with hyperkeratotic layers. In the endophytic (ulcerative, ulcerative-infiltrating) form, the initial nodule quickly undergoes ulceration with the formation of an irregular ulcer with a crater-shaped bottom. Daughter elements can form along its periphery, and when they disintegrate, the ulcer increases in size. The tumor becomes immobile and can destroy surrounding tissues, including bones and blood vessels. The deep form of squamous cell carcinoma can occur with pronounced inflammatory phenomena, which makes it similar to the pyogenic process. There is a warty form, in which the tumor is covered with warty growths, grows slowly, and rarely metastasizes. In old age, more often in men, squamous cell carcinoma can manifest itself in the form of a cutaneous horn.

An important role in the oncogenesis of squamous cell skin cancer, especially when the process is localized in the anogenital region, is attributed to human papillomavirus types 16 and 18.

A distinction is made between tumor and ulcerative skin cancer. At the onset of the disease, a papule appears, surrounded by a rim of hyperemia, which over the course of several months turns into a dense (cartilaginous consistency), fused with subcutaneous fat, slightly mobile node (or plaque) of a reddish-pink color, 1.5 cm or more in diameter, with scales or warty growths on the surface (warty variety), easily bleeding at the slightest touch, necrotizing and ulcerating.

In the papillomatous variety, more rapid growth is observed, individual elements are located on a wide base, having the shape of cauliflower or tomato.

Tumors often ulcerate within 4-5 months of their existence.

In the ulcerative type, irregularly shaped ulcers with clear edges are formed, covered with a brownish crust. The ulcer does not spread in depth, but along the periphery. In the deep form, the process spreads both in depth and along the periphery. In this case, the ulcer has a dark red color, steep edges, a bumpy bottom, and a yellowish-white coating.

Differential diagnosis

Squamous cell skin cancer should be distinguished from pseudoepitheliomatous hyperplasia, basal cell carcinoma, and Bowen's disease.

Differential diagnostics of skin cancer is carried out with precancerous conditions that are observed in actinic keratosis, cutaneous horn, warty dyskeratosis, pseudocarcinomatous hyperplasia, keratoacanthoma, etc.

In the undifferentiated form, cells with hyperchromic nuclei predominate. In this case, keratinization is not observed or is weakly expressed.

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Treatment of squamous cell skin cancer

Surgical removal of the tumor within healthy tissues is performed. Cryodestruction and photodynamic therapy are also used. The choice of treatment method depends on the prevalence and localization of the process, the histological picture, the presence of metastases and the patient's age. Tumor removal is often combined with radiotherapy.