Malignant melanoma is a rare malignant tumor of the skin, also known as nevus cancer or melanoma. It is mostly caused by long-term or repeated adverse stimulation of nevus or pigmented mother spots, and is extremely malignant, accounting for a large proportion of deaths from skin tumors. It occurs mostly in the skin or mucous membranes close to the skin, but also in the soft meninges and choroid. The incidence rate varies according to ethnicity, region and race, and is much higher in Caucasians than in Blacks. Although China is a low incidence area for melanoma, the incidence rate has been on the rise in recent years. In recent years, with the promotion of the TV series “Do Not Disturb II” and related TV health programs, the disease has received more and more attention.
Malignant melanoma is most commonly found on the skin, but can also be seen under the nails of the fingers or toes, or on the mucosa inside the mouth, vagina, or anus. Primary malignant melanoma can also be seen in the meninges, iris, and ciliary body.
Causes
It has been reported that 84% of malignant melanomas arise from benign moles. The true cause of malignant transformation of normal melanocytes is unknown and should be related to atmospheric pollution, overstimulation, frequent friction, inappropriate injury, immunodeficiency, race, etc.
The shape and size of moles often change during pregnancy, and there is no evidence that pregnancy increases the likelihood of malignant transformation of pigmented nevi to melanoma.
Signs of malignancy
If a pigmented nevus shows the following signs, early consultation should be made: accelerated growth or appearance of multiple small pigmented nevi around the original nevus, i.e. satellite foci; deepening or discoloration, especially the spread of pigmented areas to the surrounding normal skin; changes in surface features and texture and shape, especially inflammatory reactions in the skin around the nevus; occurrence of ulcers, itching or pain; breakage and bleeding when washing the face or slight touching.
Manifestation of malignant melanoma
It is more common in middle-aged and elderly people, and more men than women. It is mostly found on the feet of the lower extremities, followed by the trunk, head and neck, and upper extremities. They often appear as rapidly enlarging melanotic nodules. In the early stage, pigmentation of normal skin may occur, or pigmented nevi may increase in pigmentation and deepen in black color, and then the lesions expand continuously, and some of them are accompanied by itching and pain. The lesions may be elevated, patchy, nodular, or cauliflower-shaped. When the lesions grow into the subcutaneous tissue, they appear as subcutaneous nodules or masses. Lymph node metastasis often occurs, with advanced metastasis to lung, liver, bone, brain and other organs.
Confirmation of melanoma diagnosis
The diagnosis of melanoma can be confirmed by biopsy as soon as signs of malignancy or suspicion of malignancy are detected.
Differential diagnosis
It mainly includes basal cell carcinoma, seborrheic keratosis, dysplastic nevus, blue nevus, dermatofibroma, various pigmented nevi, etc. Skin biopsy is the most accurate method of confirming the diagnosis. Complete radical surgery must be performed only after a definite pathological diagnosis is available.
Treatment of melanoma
The treatment of melanoma is surgical excision. Although there is a debate on the extent of tumor margin excision, most experts believe that for thin lesions, ≤1mm in thickness, only 1cm of normal skin outside the tumor should be removed, and for lesions thicker than 1mm, extensive excision should be performed 3cm to 5cm from the tumor margin. For malignant melanoma located at the extremity, finger (toe) amputation is often required. Deeper lesions require radical surgery and biopsy of the anterior lymph nodes. For those with large lesions with distant metastases that are not amenable to radical surgery, palliative excision may be considered as long as conditions permit in order to relieve ulcerative bleeding or pain.
Malignant freckled nevus melanoma and malignant freckled nevus are usually treated by extensive local excision. High-dose x-ray treatment is far less effective than surgery. Malignant freckle nevi should be excised as early as possible before the lesions increase in size.
Disseminated or nodular melanoma requires extensive excision of tissue including deep fascia. If there is lymph node accumulation, the lymph nodes should be therapeutically removed and histologically examined.
Malignant melanomas with deeper invasion and those with local or distant metastases can be treated with chemotherapy (dacarbazine, nitrosourea, carmustine, romustine), but the prognosis is poor.
Ultra-extensive radical surgery may not help to improve survival, but rather have a negative impact on quality of life.
Radiation therapy
With the exception of certain very early freckled malignant melanomas that are effective for radiation therapy, the treatment is generally ineffective for primary foci. Therefore, radiation therapy is generally not used for primary lesions, but for metastatic lesions.
Chemotherapy
1.Single drug.
(1)Nitrosoureas.
(2)Nitrosoureas.
2, combination of drugs: malignant melanoma is not very sensitive to chemotherapy, but the combination of drugs can improve the efficiency and reduce toxic reactions.
Immunotherapy
The common ones are BCG vaccine, interferon, interleukin-2 (ILA-2) and lymphokine-activated killer cells (LAK cells) and other biological response modifiers.
The use of melanoma antigens as a vaccine may also be a treatment option.
Preventive measures
1. Avoid excessive sun exposure as much as possible.
2.Pigmented nevi in friction-prone areas, such as waist pigmented nevi, plantar pigmented nevi, pigmented nevi at the back of the neck and mucous membrane pigmented nevi, should be surgically removed or skin biopsy should be performed as early as possible.
3.Inappropriate methods such as needling, hand pinching, tearing, aromatherapy, lime, etc. should not be used to remove moles, and avoid scratching or repeatedly and long-term stimulation of pigmented nevi.
4. For pigmented nevi with signs of malignancy or suspected malignancy or those with darker color that are not suitable for non-surgical treatment, surgery should be performed as early as possible, and routine pathological examination should be performed after surgery.
Patient prognosis
Malignant melanoma has a high degree of malignancy and high mortality. Although there are many reasons, most of them are related to the depth of tumor infiltration, the scope and depth of surgical resection, the presence of lymph node metastasis, the location of the lesion, and even age and gender. Those with lesions ≥4mm, lymph node metastasis, lesions located in the trunk and mucosa, and incomplete surgical resection will significantly reduce the survival rate.
Early prevention, early detection, early diagnosis and early treatment are the only correct way to save patients’ lives.