Skin Cancer: Types, Symptoms, Diagnosis, Treatment
For practical purposes, skin cancer has been divided into two main groups: non-melanoma skin cancer and melanoma. Within the first group are basal cell carcinoma and squamous cell carcinoma. There are, of course, other malignant skin tumors such as carcinomas of sebaceous and sweat glands, or sarcomas.
Basal cell carcinoma (BCC) and epidermal carcinoma (EC) are the most frequent malignant neoplasms of the skin in the white population and both share the same origin in the epidermal cell, as well as epidemiological and carcinogenic characteristics. Most injuries occur on the skin exposed to sunlight, and may also occur in non-exposed areas which are more aggressive. The incidence of CE and BCC is directly related to age, residence in areas with high levels of ultraviolet radiation, as well as chronic accumulated exposure to it.
Melanoma is a malignant tumor of the skin that, in 30% of cases, may develop from an existing nevus or may appear de novo in normal-looking skin.
Basal Cell Carcinoma
Basal cell carcinoma (BCC) is the most common of all. Its cells show a morphology similar to those of the basal stratum of the epidermis, hence its name. In general terms, it is characterized by being locally invasive, slow growing and with little risk of metastasis. However, if they are not treated in a timely manner or in an adequate manner they are capable of causing great destructions of the face.
It is the most frequent cancer in the white population, in the United States the annual incidence is 146 per 100,000 inhabitants, but these figures vary worldwide, with an incidence in Australia of up to 726 per 100,000 inhabitants.
The incidence of BCC increases with age, although an increasing number of cases are currently being reported in young patients.
The most important factor involved in the formation of skin cancer is ultraviolet (UV) radiation. In recent years, the mechanisms by which the skin can develop a BCC have been described. The immunosuppression induced by UV radiation leads to a series of immunological events that induce a chronic inflation of skin cells, in addition, there are alterations in the genetic material in these cells that lead to the formation of malignant tumors.
The BCC can be presented in different, constituting clinical forms. In general, 3 fundamental types of lesions are observed: exophytic, flat, and ulcerated.
Exophytic: it appears as a hemispheric, erythematous or violaceous lesion, sometimes of lobed appearance and with telangiectasias. It is the most common clinical variety, it can be pigmented or ulcerated and can rarely take on a vegetative aspect.
Flat: it is constituted by erythematous plaques, with little infiltration, sometimes limited by a thin shiny border. It can be multiple and in those cases, it predominates in the thorax.
Ulcerated: it is characterized by ulcerated lesions from the beginning with varying degrees of infiltration and destruction of neighboring tissues.
In general, it is simple if we take into account that they have a characteristic morphology, such as the elevated edge in the periphery, an evolution that in general is related to the size of the tumor, as they grow on average 0.5 cm per year, and facial location in approximately 82% of cases. The diagnosis should be confirmed with the biopsy and the histological study.
The main objective in the treatment of this tumor is its complete elimination of the tumor with acceptable cosmetic results. Several treatment modalities are available; The choice depends on the type of tumor and the available resources. The treatment of BCC can be summarized in two large groups: surgical and non-surgical procedures. Among the surgical procedures are:
a) Destructive techniques such as curettage and electrodesiccation and cryosurgery
b) Excisional techniques, that is, surgical excision with margins and Mohs micrographic surgery.
In the group of non-surgical procedures are: Radiotherapy, intralesional 5-Fluoruracil, intralesional interferon, photodynamic therapy, chemotherapy, retinoids, and more recently imiquimod.
Squamous Cell Carcinoma
Also called spinocellular epithelioma or spiny cell carcinoma, It is a malignant neoplasm derived from the cells of the epidermis or its annexes, with the capacity to metastasize to regional lymph nodes or other organs. It has a rapid growth and appears very frequently from precancerous lesions such as actinic keratosis, chronic ulcers, or after treatments with PUVA (psoralens and ultraviolet radiation). Unlike basal cell carcinoma, it appears in the genitals, mucous membranes, palms, and soles.
This variety of skin cancer ranks 2nd in frequency, It predominates in people with white skin who are exposed excessively to solar radiation. It is more frequent in the male sex. There is a clear predominance after 60 years of age.
Squamous cell carcinoma can be triggered by chemical agents (hydrocarbons), physical means (ionizing or ultraviolet radiation), viral diseases and is favored by immunosuppression, whether by drugs, lymphoproliferative diseases, transplants or human immunodeficiency. The most important risk factors are sun exposure, fair skin, light eyes, advanced age, and smoking.
It predominates in the face (around 50%), mainly in the lower lip, cheeks and auricular pavilions. The limbs follow in frequency, being more common on the back of the hand. It can occur in the genitals, oral and anal mucosa.
The superficial variety is intraepidermal (in situ) and can remain for a long period of evolution. It is observed as an erythematous plaque of one or several centimeters, it is known as Bowen's disease or Queyrat erythroplasia if it affects the penis.
The ulcerated form is the most frequent, it is constituted by an ulcer of an anfractuous surface, infiltrated in its base, it bleeds easily and it is of rapid growth.
The keratotic nodular variety has an infiltrated base, may look like a cutaneous horn, or show central ulceration with a keratin crater.
The vegetative form often develops on chronic inflammatory lesions and can reach large dimensions.
The choice of the therapeutic method will depend on a series of considerations regarding location, size, depth, degree of histological differentiation, and clinical status. It can be surgical, or use radiotherapy and in advanced cases chemotherapy.
It is a neoplasm of melanocytes that affects the skin in 90% of cases but can appear in mucous membranes, eyeball, leptomeninges, and gastrointestinal tract. It has a great ability to metastasize. This tumor is the cause of 75% of deaths from skin cancer. Early diagnosis is particularly important since survival decreases drastically when the neoplasm deepens in the dermis. It is much more frequent in Caucasians. The average age is around 52 years old, being exceptional in childhood.
Etiopathogenesis It is not known exactly, however it is known of multiple factors such as
• genetic predisposition
• exposure to environmental substances whether chemical, virus or ionizing radiation
• exposure to ultraviolet light.
There are characteristics of the individual that predispose to a greater risk to develop melanoma that can be summarized as follows:
• White skin, blond or red hair, light eyes
• Inability to tan, a tendency to sunburn
• Increase in the number of moles, or atypical nevi
• Presence of congenital nevi
• A family history of melanoma
There are four basic types of melanoma that have different histological, clinical and behavioral characteristics:
Melanoma malignant lentigo: It is observed in the face or neck, in people of advanced ages, as an irregular hyperpigmented spot of long evolution. It is the least aggressive, it can remain "in situ" for several years when there is induration or ulceration, indicating its progression towards an invasive melanoma.
Melanoma of superficial extension: At the beginning it is a flat lesion, with different pigmentation tones, the normal folds of the skin are lost, as it advances it can show an infiltrated or elevated area, this form is more common in the white race.
Nodular melanoma: It is a protruding tumor, whose surface can be smooth or vegetative, almost black or bluish in color. The pigment may lack or be very scarce and it is known as amellanic and may be confused with other entities. This variety almost from the beginning has vertical growth and is invasive, with a tendency to spread.
Acral lentiginous melanoma: It begins as a macular lesion, with irregular pigmentation of various shades, extending peripherally or radially, to later become infiltrated. It is located in the palmar or plantar region or subungual areas of hands and feet.
It is one of the most responsible problems in clinical practice. In advanced cases it is relatively simple, however, what matters is the early diagnosis. The doctor must recognize among all the pigmented lesions when examining a pigmented lesion the following characteristics that can help the diagnosis should be evaluated. Asymmetry, irregular edges, color changes, increased diameter, elevated surface.
Other data that should be taken into account are the presence of inflammation, bleeding, pruritus, ulceration or scabs and take into account that any change in size, color or shape of a pigmented lesion must be suspicious of melanoma.
Surgery is until now the treatment of choice in early stages. In melanomas in situ such as malignant lentigo melanoma may be sufficient with only .5 to 1 cm of normal-looking skin margin, in melanomas 1 mm deep the margin may be 1 cm. In tumors of more than 1-4 mm margins can range between 1.5 to 3 cm.
In advanced cases, adjuvant treatment with immunotherapy (such as nivolumab, ipilimumab or interferon) is applied.
Chemotherapy can help some people with melanoma in advanced stages. Immunotherapy or targeted molecular drugs that are used most often, either alone or in combination with other medications.
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