出国医疗

什么基底细胞癌和鳞状细胞癌?

来源:再生之旅    时间:2013-11-12 14:45  浏览次数:

                      What are basal and squamous cell skin cancers?
                              什么基底细胞癌和鳞状细胞癌?
To understand basal and squamous cell skin cancers, it helps to know about the normal structure and function of the skin.
学习基底细胞癌和鳞状细胞癌,也有利于了解皮肤的基本结构和功能。
Normal skin
正常皮肤
The skin is the largest organ in your body. It does many different things:
皮肤是人体最大的器官,很多功能:
· Covers the internal organs and helps protect them from injury
· Serves as a barrier to germs such as bacteria
· Prevents the loss of too much water and other fluids
· Helps control body temperature
· Protects the rest of the body from ultraviolet (UV) rays
· Helps the body make vitamin D
· 保护机体内脏器官。
· 免疫屏障,防止感染。
· 阻止水分或其他液体的流失
· 调节体温
· 阻止机体遭受紫外线辐射
· 有利维生素D的生成 。
The skin has 3 layers: the epidermis, the dermis, and the subcutis (see picture).
                
Epidermis
上皮组织

The top layer of skin is the epidermis. The epidermis is thin, averaging only 0.2 millimeters thick (about 1/100 of an inch). It protects the deeper layers of skin and the organs of the body from the environment.
皮肤最顶层是上皮组织。上皮组织很薄,平均仅有0.2毫米厚。防止机体内脏器官遭受外环境的损伤。

Keratinocytes are the main cell type of the epidermis. These cells make an important protein called keratin that helps the skin protect the rest of the body.
The outermost part of the epidermis is called the stratum corneum. It is composed of dead keratinocytes that are continually shed as new ones form. The cells in this layer are called squamous cells because of their flat shape.

Living squamous cells are found just below the stratum corneum. These cells have moved here from the lowest part of the epidermis, the basal layer. The cells of the basal layer, called basal cells, continually divide to form new keratinocytes. These replace the older keratinocytes that wear off the skin's surface.

Cells called melanocytes are also found in the epidermis. These skin cells make a brown pigment called melanin. Melanin gives the skin its tan or brown color. It protects the deeper layers of the skin from some of the harmful effects of the sun. When skin is exposed to the sun, melanocytes make more of the pigment, causing the skin to tan or darken.

The epidermis is separated from the deeper layers of skin by the basement membrane. This is an important structure because when a skin cancer becomes more advanced, it generally grows through this barrier and into the deeper layers.
Dermis
The middle layer of the skin is called the dermis. The dermis is much thicker than the epidermis. It contains hair follicles, sweat glands, blood vessels, and nerves that are held in place by a protein called collagen. Collagen, made by cells called fibroblasts, gives the skin its elasticity and strength.

Subcutis

The deepest layer of the skin is called the subcutis. The subcutis and the lowest part of the dermis form a network of collagen and fat cells. The subcutis helps the body conserve heat and has a shock-absorbing effect that helps protect the body's organs from injury.

Types of skin cancer

Melanomas

Cancers that develop from melanocytes, the pigment-making cells of the skin, are called melanomas. Melanocytes can also form benign growths called moles. Melanoma and moles are discussed in our document, Melanoma Skin Cancer.
Skin cancers that are not melanoma are sometimes grouped together as non-melanoma skin cancers because they tend to act very differently from melanomas.
 
Keratinocyte cancers

These are by far the most common skin cancers. They are called keratinocyte carcinomas or keratinocyte cancers because when seen under a microscope, their cells share some features of keratinocytes, the most common cell type of normal skin. Most keratinocyte cancers are basal cell carcinomas or squamous cell carcinomas.

Basal cell carcinoma

This is not only the most common type of skin cancer, but the most common type of cancer in humans. About 8 out of 10 skin cancers are basal cell carcinomas (also called basal cell cancers). They usually develop on sun-exposed areas, especially the head and neck. Basal cell carcinoma was once found almost entirely in middle-aged or older people. Now it is also being seen in younger people, probably because they are spending more time out in the sun.
When seen under a microscope, basal cell carcinomas share features with the cells in the lowest layer of the epidermis, called the basal cell layer. These cancers tend to grow slowly. It is very rare for a basal cell cancer to spread to nearby lymph nodes or to distant parts of the body. But if a basal cell cancer is left untreated, it can grow into nearby areas and invade the bone or other tissues beneath the skin.

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