Skin cancer is a malignant tumor disease of the skin that occurs as a result of atypical transformation of its cells and is characterized by significant polymorphism. There are 4 main types: squamous cell, basal cell, adenocarcinoma and melanoma, each of which in turn has several clinical forms. Diagnosis includes examination of the entire skin, dermatoscopy and ultrasound of altered skin areas and tumor nodes, sciascopy of pigmented neoplasms, examination and palpation of lymph nodes, cytology of smear prints and histological examination. Treatment consists in its removal as completely as possible, radiation therapy, photodynamic effects and chemotherapy.
Among the total number of malignant tumors, skin cancer accounts for about 10%. Currently, dermatology notes a trend towards an increase in morbidity with an average annual increase of 4.4%. Most often, skin cancer develops in elderly people, regardless of their gender. The most predisposed to the occurrence of the disease are light-skinned people, people living in conditions of increased insolation (hot countries, high-altitude areas) and staying outdoors for a long time.
In the overall structure of skin cancer, 11-25% is squamous cell carcinoma and about 60-75% is basal cell carcinoma. Since the development of squamous cell and basal cell skin cancer occurs from the cells of the epidermis, these diseases are also referred to as malignant epitheliomas.
Among the causes of malignant degeneration of skin cells, excessive ultraviolet radiation is in the first place. This is proved by the fact that almost 90% of skin cancers develop in open areas of the body (face, neck), most often exposed to radiation. Moreover, for people with fair skin, exposure to UV rays is the most dangerous.
The occurrence can be triggered by exposure to various chemicals that have a carcinogenic effect on it: tar, lubricants, arsenic, tobacco smoke particles. Radioactive and thermal factors acting on the skin can lead to the appearance of cancer. So, skin cancer can develop at the site of a burn or as a complication of radiation dermatitis. Frequent traumatization of scars or moles can cause their malignant transformation with the appearance of skin cancer.
Predisposing to the appearance may be hereditary features of the body, which causes family cases of the disease. In addition, some skin diseases have the ability to undergo malignant degeneration into skin cancer over time. Such diseases belong to precancerous conditions. Their list includes Keir’s erythroplasia, Bowen’s disease, pigmented xeroderma, leukoplakia, senile keratoma, cutaneous horn, Dubreuil melanosis, melanoma-threatening nevi (complex pigmented nevus, blue nevus, giant nevus, Ota nevus) and chronic inflammatory skin lesions (trophic ulcers, tuberculosis, syphilis, SLE, etc.).
The following forms of skin cancer are distinguished:
- Squamous cell skin cancer (squamous cell carcinoma) – develops from flat cells of the surface layer of the epidermis.
- Basal cell skin cancer (basal cell carcinoma) — occurs with atypical degeneration of the basal cells of the epidermis, which have a rounded shape and are located under a layer of flat cells.
- Adenocarcinoma of the skin is a rare malignant tumor that develops from the sebaceous or sweat glands.
- Melanoma is a skin cancer that arises from its pigment cells — melanocytes. Taking into account a number of features of melanoma, many modern authors identify the concept of “skin cancer” only with non-melanoma cancer.
To assess the prevalence and stage of the process in non-melanoma skin cancer, the international TNM classification is used.
T — the prevalence of the primary tumor:
- TX — it is impossible to assess the tumor due to lack of data
- THAT is, the tumor is not detected.
- Tis — cancer in place (preinvasive carcinoma).
- TI is the size of the tumor up to 2 cm.
- T2 — the size of the tumor is up to 5 cm.
- TK — the size of the tumor is more than 5 cm .
- T4 — skin cancer grows into underlying deep tissues: muscles, cartilage or bones.
N — condition of lymph nodes:
- NX — it is impossible to assess the condition of regional lymph nodes due to lack of data.
- N0 — signs of metastases to regional lymph nodes were not detected.
- N1 — there is a metastatic lesion of regional lymph nodes.
M — presence of metastasis:
- MX — lack of data on the presence of distant metastases.
- MO — signs of distant metastases were not detected.
- M1 — the presence of distant metastases of skin cancer.
The degree of differentiation of tumor cells is assessed within the limits of the histopathological classification of skin cancer.
- GX — there is no way to determine the degree of differentiation.
- G1 — high differentiation of tumor cells.
- G2 is the average differentiation of tumor cells.
- G3 — low differentiation of tumor cells.
- G4 is an undifferentiated skin cancer.
Squamous cell carcinoma of the skin is characterized by rapid growth and spread both over the surface of the skin and in depth. The growth of the tumor into the tissues located under the skin (muscle, bone, cartilage) or the addition of inflammation is accompanied by the appearance of pain syndrome. Squamous cell skin cancer can manifest as an ulcer, plaque or node.
The ulcerative variant of squamous cell carcinoma of the skin has the appearance of a crater-shaped ulcer surrounded, like a roller, by dense raised and steeply ending edges. The ulcer has an uneven bottom, covered with crusts of dried serous-bloody exudate. It gives off a rather unpleasant smell. The plaque of squamous cell carcinoma of the skin is characterized by a bright red color, dense consistency and a bumpy surface. It often bleeds and rapidly increases in size.
The coarse-grained surface of the node in squamous cell skin cancer makes it look like a cauliflower or mushroom. A high density, bright red or brown color of the tumor node is characteristic. Its surface may erode or ulcerate.
Basal cell skin cancer has a more benign and slow course than squamous cell. Only in advanced cases, it germinates the underlying tissues and causes soreness. Metastasis is usually absent. Basal cell carcinoma of the skin is characterized by a large polymorphism. It can be represented by nodular-ulcerative, warty, perforating, scar-atrophic, pigmented, nodular, sclerodermiform, flat surface and “turban” forms. The onset of most clinical variants of basal cell carcinoma occurs with the formation of a single small nodule on the skin. In some cases, neoplasms may be multiple in nature.
Adenocarcinoma of the skin most often occurs in areas rich in sweat and sebaceous glands. These are armpits, inguinal region, folds under the mammary glands, etc. adenocarcinoma begins with the formation of an isolated node or papule of small size. This rare type is characterized by slow growth. Only in some cases, adenocarcinoma can reach large sizes (about 8 cm in diameter) and germinate muscles and fascia.
Melanoma in most cases is a pigmented tumor that has a black, brown or gray color. However, cases of depigmented melanomas are also known. During the growth of melanoma skin cancer, horizontal and vertical phases are distinguished. Its clinical variants are represented by lentigo-melanoma, surface-spreading melanoma and nodular melanoma.
Skin cancer, spreading deep into the tissues, causes their destruction. Given the frequent localization on the face, the process can affect the ears, eyes, paranasal sinuses, the brain, which leads to hearing and vision loss, the development of sinusitis and meningitis of malignant origin, damage to vital brain structures up to death.
Metastasis occurs primarily through lymphatic vessels with the development of malignant lesions of regional lymph nodes (cervical, axillary, inguinal). At the same time, the compaction and enlargement of the affected lymph nodes, their painlessness and mobility during probing are revealed. Over time, the lymph node is soldered to the surrounding tissues, as a result of which it loses mobility. Soreness appears. Then the lymph node disintegrates with the formation of an ulcerative defect of the skin located above it.
The spread of cancer cells with blood flow leads to the formation of secondary tumor foci in the internal organs with the development of lung cancer, stomach, bone, liver, brain tumor, breast cancer, kidney cancer, malignant tumor of the adrenal gland.
Patients with suspected skin cancer should be consulted by a dermatologist. The doctor examines the formation and other skin areas, palpation of regional lymph nodes, dermatoscopy. Determination of the depth of tumor germination and the prevalence of the process can be performed using ultrasound. For pigmented formations, siascopy is additionally indicated.
Only cytological and histological examination can definitively confirm or refute the diagnosis of skin cancer. Cytological examination is performed by microscopy of specially colored smears-prints made from the surface of cancerous ulcers or erosions. Histological diagnosis of skin cancer is carried out on the material obtained after removal of the neoplasm or by skin biopsy. If the integrity of the skin above the tumor node is not violated, then the biopsy material is taken by the puncture method. According to the indications, a biopsy of the lymph node is performed. Histology reveals the presence of atypical cells, establishes their origin (flat, basal, melanocytes, glandular) and the degree of differentiation.
When diagnosing skin cancer, in some cases, its secondary nature should be excluded, that is, the presence of a primary tumor of internal organs. This is especially true for adenocarcinomas of the skin. For this purpose, ultrasound of the abdominal cavity organs, lung x-ray, kidney CT, contrast urography, skeletal scintigraphy, MRI and CT of the brain, etc. are performed. The same examinations are necessary in the diagnosis of distant metastases or cases of deep germination of skin cancer.
The choice treatment method is determined in accordance with its type, the prevalence of the process, the degree of differentiation of cancer cells. The localization of skin cancer and the age of the patient are also taken into account.
The main task in the treatment is its radical removal. Most often it is performed by surgical excision of pathologically altered tissues. The operation is performed with the capture of apparently healthy tissues by 1-2 cm. Microscopic intraoperative examination of the marginal zone of the removed formation allows performing the operation with minimal seizure of healthy tissues with the most complete removal of all tumor cells of skin cancer. Excision of skin cancer can be performed using a neodymium or carbon dioxide laser, which reduces bleeding during surgery and gives a good cosmetic result.
Electrocoagulation, curettage or laser removal can be applied to small-sized tumors (up to 1-2 cm) with a slight germination of skin cancer into the surrounding tissues. When performing electrocoagulation, the recommended capture of healthy tissues is 5-10 mm. Superficial highly differentiated and minimally invasive forms of skin cancer can undergo cryodestruction with the capture of healthy tissues by 2-2.5 cm. Since cryodestruction does not leave an opportunity for histological examination of the removed material, it can be performed only after a preliminary biopsy with confirmation of a small spread and high differentiation of the tumor.
Skin cancer that covers a small area can be effectively cured with the help of close-focus X-ray therapy. For the treatment of superficial, but large formations of skin cancer, electron beam irradiation is used. Radiation therapy after removal of the tumor formation is indicated for patients with a high risk of metastasis and in case of recurrence of skin cancer. Radiation therapy is also used to suppress metastases and as a palliative method in the case of inoperable skin cancer.
It is possible to use photodynamic therapy of skin cancer, in which irradiation is carried out against the background of the introduction of photosensitizers. With basal cell carcinoma, local chemotherapy with cytostatics gives a positive effect.
Mortality rates for skin cancer are among the lowest in comparison with other oncological diseases. The prognosis largely depends on the type of skin cancer and the degree of differentiation of tumor cells. Basal cell skin cancer has a more benign course without metastasis. With adequately carried out timely treatment of squamous cell skin cancer, the 5-year survival rate of patients is 95%. The most unfavorable prognosis is in patients with melanoma, in which the 5-year survival rate is only 50%.
Preventive measures aimed at preventing skin cancer consist in protecting the skin from the effects of adverse chemical, radiation, ultraviolet, traumatic, thermal, and other influences. It is necessary to avoid open sunlight, especially during the period of the greatest solar activity, use various sunscreens. Chemical industry workers and persons associated with radioactive radiation must comply with safety regulations and use protective equipment.
It is important to monitor patients with precancerous skin diseases. Regular examinations by a dermatologist or dermatooncologist in such cases are aimed at timely detection of signs of degeneration of the disease into skin cancer. Prevention of the transformation of melanoma-threatening nevi into skin cancer lies in the correct choice of therapeutic tactics and the method of their removal.