Skin becomes darker

Introduction The darkening of the skin is a clinical manifestation of malignant melanoma of the skin. Malignant melanoma of skin (MM) is a malignant tumor originating from normal melanocytes or primitive sputum cells. Although it is rarer than skin cancer, it has a high degree of malignancy, rapid progress, sinister condition and prognosis. Very poor.

Cause

(1) Causes of the disease

The etiology of melanoma has not been fully elucidated. Some research data suggest that its occurrence is related to the following factors:

1. cell malignant transformation: In the past, it was thought that skin MM originated from the malignant transformation of sputum cells, especially junctions. In recent years, it has been considered that skin MM is related to sputum cell sputum, but it is not entirely true. MM cells are derived from intradermal dermal sputum cells rather than so-called borderline sputum cells. According to statistics, the MM occurring in the trunk or limbs (except palm and sputum) is 35% to 50%, which is related to the original intradermal dermal cells. Undoubtedly, primary skin MM can originate from the original melanocytes in the epidermis and some of the pre-existing congenital (usually large, such as congenital giant python) and acquired intradermal sputum cell sputum. However, about 1/3 of MM patients have no history of sputum cell history. For example, Clark (1969) has histological observation of two groups (209 cases and 60 cases each), only 20 cases (9.6%) and 5 cases ( 8.3%) is related to sputum cell sputum. In addition, MM occurs in exposed areas such as face and scalp. This is not a good site for sputum cell sputum. Most of the palm and ankle MM are not related to sputum cell sputum. Therefore, some people think that MM is not completely related to sputum cell sputum. However, any sputum including pigmented skin lesions, when sudden growth accelerates, pigmentation darkens or becomes shallow, irregular pigmented halos appear around, or pigmentation halo, itching, tingling, surface scaling, secretion, scarring , ulceration, hemorrhage, hair loss, satellite nodules in the vicinity, or regional lymph node enlargement with unexplained causes should be considered as an indication of the beginning of malignant transformation, which requires careful attention.

2. Ultraviolet radiation: repeated exposure to ultraviolet light at a wavelength of 290 to 320 nm can not only increase the number of melanocytes, but also cause changes in their quality. The incidence of MM is related to the exposure of sunlight, especially ultraviolet light. The incidence of MM in the South of Norway is almost twice that of the North. According to Israeli statistics, the incidence of agricultural workers MM (15.4/100,000 per year) is higher than in cities (1.7/10 million per year); coastal areas (3.5/100,000 per year) are higher than mountains (2.0/10 million per year). Some people think that malignant freckle-like MM is related to direct sunlight. Non-exposed parts of nodular MM may be due to sunlight. The exposed skin releases a substance into the blood (daylight cycle factor) and acts on non-exposure sites. Caused by melanocytes of the skin.

3. Race: Caucasians have a higher incidence of MM than people of color. The incidence of Caucasians in the United States can be as high as 42/100,000 per year, while that of blacks is only 0.8/100,000 per year.

4. Genetics: Patients with family members are susceptible to this disease. Anderson (1971) reported 74 of the 22 families. Identical twin patients have also been reported. The age of onset of familial patients is about 10 years earlier than usual. Some hereditary skin diseases such as xeroderma pigmentosum can occur in 50% of patients with this disease.

5. Trauma and irritation: This disease often occurs in the scalp, palms, soles and other areas often suffering from friction. Many young female patients often have a history of pointing many years ago. It is estimated that 10% to 60% of patients have a history of trauma, including crush, stab wound, blunt injury, armor, burn or X-ray.

6. Viral infection: Virus-like particles were found in MM cells of voles and humans.

7. Immune response: This disease is more common in the elderly, and the incidence increases with age. In addition, there may be a self-resolving phenomenon, indicating that the occurrence of this disease has a certain relationship with the patient's immune response.

(two) pathogenesis

1. Histopathology: typical melanoma, under the microscope, melanocytes are abnormally proliferated, and some cell nests are formed in the epidermis or in the epidermis-dermis. These cell nests vary in size and can fuse with each other. This condition is rarely seen in pigmented nevus. The size and shape of melanocytes in the nest, as well as the shape of the nucleus, vary to varying degrees. Mitosis (including abnormal mitosis) is more common than benign pigmented nevus. The nucleolus is usually an eosinophilic "bird's eye". In invasive melanoma, melanoma cells can be seen in the dermis or subcutaneous tissue.

(1) Freckle-like melanoma: In the brown, brown and black areas of the lesion, the morphology of melanocytes in the epidermis varies greatly. In the brown area, the number of melanocytes increases, some cells are normal, some are larger than normal cells, and some are typical or weird. All cells are distributed along the basement membrane. In the flat black area, many different types of melanocytes replace the basement membrane, forming a band along the epidermal-dermal interface, with keratin cells above it and a dermal papilla below it. At the epidermal-dermal interface, significant hyperpigmentation and keratinized epidermal atrophy were observed, accompanied by extensive atypical melanocyte proliferation. Intensive lymphocytes and melanin-rich macrophages are infiltrated in the adjacent dermal papilla. In certain areas of the dermis, melanoma cells are seen to invade, forming large cell nests that correspond to clinically seen nodules.

(2) superficial spreading melanoma: groups of melanocytes are malignant, unlike freckle-like melanoma, melanoma cells are polymorphic. In the tumor, there is a slightly bulged and pigmented part. Under the microscope, large melanocytes in the epidermis are shown in the pagetoid distribution. These large melanocytes can appear individually or nested. In the nodule part of the tumor, there is a dense accumulation of tumor cells in the dermis. Large melanocytes are also seen in the invading area. These cells, rich in cytoplasm, contain finely distributed pigment particles, and the entire cell is "dusty". Occasionally, the tumor cells in superficial spreading melanoma are spindle-like.

(3) Typical nodular melanoma: Tumor cells originate from the epidermis-dermis junction, and can invade the epidermis and dermis upward and downward, respectively, especially in the tendency to invade into the dermis. In the area outside the invaded epidermis, no atypical melanoma cells are seen, which may be expressed as epithelial cells or spindle cells.

(4) acne-like sputum-type melanoma: In the plaque area, microscopic melanocyte proliferation, nuclear enlargement, and chromatin type are not typical. The cytoplasm is filled with melanin particles, which are long in dendritic and can extend to the granular layer. In the area of the papules or nodules, the tumor cells are usually fusiform and extend to the dermis.

2. Pathological grading

(1) Grading according to invasion depth: After studying the relationship between the depth of invasion of melanoma and prognosis, Clark (1969) classified the melanoma into 5 grades according to the depth of invasion. The higher the grade, the worse the prognosis.

Grade I: Tumor cells are restricted to the epidermis above the basement membrane.

Grade II: Tumor cells break through the basement membrane and invade the dermal papilla.

Grade III: The tumor cells are filled with the dermal papilla layer and further invade downward, but not to the dermal reticular layer.

Grade IV: Tumor cells have invaded the dermal reticular layer.

Grade V: The tumor cells have passed through the dermal reticular layer and invaded the subcutaneous fat layer.

(2) Vertical thickness grading: Breslow (1970) studied the relationship between the vertical thickness of melanoma and the prognosis. According to the thickest part of the melanoma measured by the eyepiece micrometer (the thickness from the granular layer to the deepest part of the melanoma), it will be black. The tumor is divided into 5 levels: less than 0.75MM, 0.76~1.50MM, 1.51~3.00MM, 3.01~4.50MM and ?4.50MM. The greater the thickness, the worse the prognosis. This microscopic fractionation method has been widely adopted in the future and has proven to be of great value in judging prognosis.

an examination

Related inspection

Immunopathological examination of urine analysis

1. Histopathological examination: melanocytes are abnormally proliferated, and there are cell nests in the epidermis or epidermis-dermis. The nucleolus is usually an eosinophilic "bird's eye". In invasive melanoma, melanoma cells can be seen in the dermis or subcutaneous tissue.

For a typical melanoma, a general HE staining section pathology examination can confirm the diagnosis. However, atypical melanoma, such as non-pigmented melanoma, often need to be supplemented with special techniques (such as S-100 and HMB-45 immunohistochemical examination) to help diagnose.

2. Urine examination: When there is a large amount of melanin and its metabolites in the urine and it is black urine, it is helpful for the diagnosis of melanoma.

X-ray film, B-ultrasound, CT, MRI and radionuclide scanning tests can help to determine whether the black tumor has lung, liver, kidney, brain and other visceral metastases.

Differential diagnosis

It needs to be distinguished from the following symptoms:

The red skin that has not subsided for a long time: the red skin that has not subsided for a long time, which shows the possibility of alerting the skin in situ when it is mildly erosive.

Vasospasm: Vasospasm is the most common benign tumor in infants and is formed by the proliferation of vascular network in the embryonic stage. There are two types of vasospasm, hemangioma and vascular malformation.

Darkening of the skin: pigmentation, which is dominated by an increase in the number of melanocytes, can cause skin darkening.

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