Vulvar melanoma is a malignant tumor originating from melanocytes and located in the area of the labia majora, clitoris or labia minora. It is manifested by itching, burning sensation, pain, unpleasant odor, enlargement of inguinal lymph nodes, dysuric disorders or discomfort when urinating. A voluminous formation is palpated in the lesion area. When the tumor ulcerates, bleeding occurs. The diagnosis is established on the basis of clinical symptoms, examination data and additional studies. Treatment – surgery, chemotherapy, immunotherapy.
General information
Vulvar melanoma is a malignant neoplasm arising from epidermal melanocytes, less often from a pigmented nevus. It is located in the area of the external female genitalia. It is about 2% of the total number of melanomas and 8-11% of the total number of malignant tumors of the vulva. It is the second most common oncological disease in this area after squamous cell carcinoma. Vulvar melanoma more often affects white women of post-menopausal age. It is considered a prognostically unfavorable disease, which is associated with both high malignancy of melanomas and late diagnosis due to the absence of specific symptoms. The treatment is carried out by specialists in the field of oncology and gynecology.
Pathological anatomy
Data on the frequency of lesions of different areas of the vulva vary. Some experts say that in 50% of cases, vulvar melanoma is located in the labia majora, and the clitoris and labia minora areas account for 25% of the total number of tumors. Others believe that the disease more often affects the clitoris and labia minora. Information about the origin of the tumor is also contradictory. It is generally recognized that vulvar melanoma often develops from melanocytes in an unchanged area of the skin. At the same time, opinions on the probability of rebirth of nevi differ.
Some oncologists say that every fourth melanoma of the vulva occurs at the site of a pigmented, borderline or mixed nevus, which indicates the need for oncological alertness regarding the pigmented formations of this area. Others believe that malignant degeneration of the nevi of the vulva area is extremely rare. Externally, melanoma may resemble a polyp or a nodule protruding above the surface of the skin. In 5% of cases, an ulcerative surface is detected.
Two thirds of the vulvar melanomas are pigmented, the rest are devoid of pigmentation. Every fifth tumor is surrounded by satellite nodules – small tumor-like formations resembling millet grains. Metastases to regional lymph nodes are detected in 24-74% of patients. Despite the unilateral localization of the tumor, some patients have a bilateral lesion of the inguinal-femoral nodes. Hematogenous metastasis is possible in the absence of metastases to regional lymph nodes. Vulvar melanoma usually metastasizes to the liver and lungs, less often to the bones, adrenal glands, kidneys and brain. Damage to other organs and tissues is not excluded.
Classification
Taking into account histological features, three forms of vulvar melanoma are distinguished: superficial (4%), nodular (20%) and mucosal lentigious (52%). Mixed unclassifiable forms are detected in 24% of patients. The mucous lentigious form mainly affects the vestibule of the vagina and the clitoris area. Superficial and mucous lentigious melanomas of the vulva grow both horizontally and vertically, nodular melanoma – mainly vertically. The latter type of tumor quickly penetrates deep into the underlying tissues and has the most unfavorable prognosis.
One of the main prognostic criteria for vulvar melanoma is the depth of invasion, so experts widely use Clark’s classification, compiled taking into account this indicator:
- Level 1 – the neoplasm does not go beyond the epidermis. There are no metastases in noninvasive tumors.
- Level 2 – malignant cells penetrate into the papillary layer of the dermis to a depth of no more than 1 mm. Metastases at this level of invasion are detected in 5% of patients.
- Level 3 – vulvar melanoma sprouts the papillary layer of the dermis to a depth of 1.1-2 mm. Metastases at this level of invasion are found in 50% of patients.
- Level 4 – the neoplasm penetrates into the reticular layer of the dermis.
- Level 5 – melanoma goes beyond the skin and sprouts subcutaneous fat.
Taking into account the cellular composition, there are four types of vulvar melanomas: fusiform, epithelioid, polymorphic and resembling nevus. About a quarter of tumors are not classified by a specific type.
Symptoms
Patients may complain of pain, itching, burning sensation or irritation. There may be an increase in inguinal lymph nodes, an unpleasant smell, urination disorders or discomfort when urinating. With ulceration of vulvar melanoma, scanty spotting bloody or sucrovichnye discharge appears. Some patients manage to examine a pigmented or discolored area of the skin or to feel a tumor-like formation in the area of the external genitalia.
Vulvar melanomas that have arisen in the area of unchanged skin, as a rule, cause greater oncological alertness compared to malignated congenital or acquired pigmented nevi. There are a number of signs that facilitate the recognition of malignant degeneration of such nevi. Suspicion of vulvar melanoma should arise with rapid growth and increase in the density of the nevus, darkening or depigmentation of the nevus, a focus of hyperemia around the pigment formation, ulceration, bleeding or cracks on the surface of the nevus, the appearance of satellite nodules and papillomatous outgrowths, as well as an increase in regional lymph nodes.
Diagnosis and treatment
The diagnosis is established on the basis of complaints, general and gynecological examination data and histological examination results. Biopsy for vulvar melanoma is categorically contraindicated due to the danger of spreading the process during any invasive procedures. The main method of sampling is the removal of smears-prints. To identify distant metastases, patients with vulvar melanoma are referred for liver ultrasound, chest X-ray, bone scintigraphy and radiography, adrenal ultrasound, adrenal CT, brain MRI, brain CT and other studies.
Treatment tactics are determined taking into account the prevalence of the process. With vulvar melanomas with a thickness of less than 0.75 mm, surgical excision of the neoplasm is performed from 1 cm of the surrounding unchanged tissues on the surface and 1-2 cm in depth. With neoplasms 0.75-2 mm thick, the volume of excised healthy tissues is increased to 3 or more cm. In vulvar melanomas surrounded by satellite nodules, the volume of excised tissues is measured from the edge of the most distant satellite. Then an urgent intraoperative histological examination is performed. When malignant cells are detected in the edge of excised tissues, the volume of surgical intervention is increased.
In the presence of metastases to the regional lymph nodes, inguinal-femoral lymphadenectomy is performed. With vulvar melanomas without signs of metastasis, the tactics are determined individually. Experts point to a high probability of developing regional micrometastases (in the absence of clinical signs, malignant cells in the inguinal-femoral lymph nodes are detected in 25-50% of patients). With this in mind, in doubtful cases, preventive lymphadenectomy is performed even with apparently unchanged lymph nodes. In the postoperative period, tumor chemotherapy and immunochemotherapy are prescribed. When generalizing the process, surgical intervention is not indicated, polychemotherapy and immunotherapy are used.
Vulvar melanoma is an extremely malignant neoplasm with a high tendency to metastasis. The prognosis is unfavorable except for tumors that do not go beyond the epidermis. The total five-year survival rate is 21.7-54%. In more than half of cases, the life expectancy of patients with vulvar melanoma does not exceed 2 years from the moment of diagnosis. There is a high tendency to relapse, the frequency of relapses does not depend on the tactics of treatment of the primary tumor.
