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Melanoma is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. It is one of the most aggressive forms of skin cancer and requires prompt intervention to ensure the best possible prognosis. This blog post explains the diagnosis of melanoma, and its surgical and medical treatment options.
The process of diagnosing melanoma begins with a comprehensive clinical examination. A dermatologist meticulously inspects all visible skin surfaces as well as mucous membranes, with particular attention to areas that are typically difficult to examine. Tools such as a dermoscope or a clinical microscope are often employed to enhance the visibility of the skin lesions, allowing the dermatologist to better differentiate between malignant and benign formations.
When melanoma is suspected, the preferred method of diagnosis is an excisional biopsy. This procedure involves the removal of the entire lesion along with a small margin of surrounding healthy tissue to ensure complete excision. The excised tissue is then sent for histological analysis, where it is examined under a microscope to confirm the presence of cancer cells.
An incisional biopsy, where only a part of the lesion is removed, is generally avoided in the diagnosis of melanoma. This approach poses a risk of spreading tumor cells, although it may be considered in specific scenarios where removing the entire lesion could lead to significant functional or cosmetic impairment.
To assess the spread of the disease, various imaging tests are conducted. These may include a chest X-ray and a liver ultrasound to check for distant metastases. In more advanced cases, additional imaging techniques such as CT scans or MRIs might be necessary. If there is a suspicion of cancer spreading to the lymph nodes, a fine needle aspiration biopsy can be performed to obtain a tissue sample from the affected node for further pathological examination.
The sentinel lymph node biopsy is a diagnostic procedure employed in the management of melanoma and various other cancers. The sentinel lymph node refers to the primary lymph node that receives drainage from the area of the skin affected by the tumor. This node is important because it is the first to encounter lymphatic spread from the cancerous site.
To determine whether cancer cells have metastasized beyond the original tumor site, the sentinel lymph node is identified and excised for detailed examination. This is done using a specialized technique where a radioactive tracer or sometimes a blue dye is injected into the dermis surrounding the melanoma or the scar from its surgical removal. This procedure is known as lymphoscintigraphy, which helps in mapping the lymphatic drainage and pinpointing the sentinel lymph node.
If this node tests positive for cancer cells (micrometastases), it indicates a likelihood of spread to additional lymph nodes, necessitating their removal as part of the cancer treatment. Conversely, if the sentinel lymph node is found to be free of cancer cells, it is generally assumed that the cancer has not metastasized to other lymph nodes, potentially sparing the patient from more extensive lymph node surgery.
This technique is particularly recommended for melanomas that are more than 0.76 millimeters in thickness, as thinner melanomas have a lower risk of spreading to lymph nodes. Sentinel lymph node biopsy is a minimally invasive procedure that can significantly influence the treatment and prognosis in cancer care, providing important information while minimizing unnecessary surgical intervention.
The primary goal of surgical treatment for melanoma is the complete removal of the cancerous tumor to prevent further spread and recurrence. This is typically achieved through excisional surgery, where the tumor is removed along with a margin of surrounding healthy skin to ensure all malignant cells are excised. The extent of this healthy skin margin is carefully determined based on the thickness of the melanoma.
For melanomas that are less than 1 millimeter thick, a smaller margin of healthy skin may be sufficient. However, for thicker melanomas, larger margins are required to improve the likelihood of removing all cancerous cells. The excision also often includes the underlying subcutaneous tissue, which might harbor unseen metastases.
When melanoma has spread to the lymph nodes (lymph node metastases), surgical intervention becomes more complex. The procedure typically involves the surgical removal of the affected lymph nodes to prevent further dissemination of the disease. For melanomas that are over 1 millimeter in thickness, a selective lymph node dissection is usually performed. This procedure is guided by the results of the aforementioned sentinel lymph node biopsy.
In cases where melanoma has metastasized beyond the immediate region to more distant parts of the body, surgical therapy is still an option but is generally reserved for cases where the metastases are accessible and can be removed without excessive risk. This type of surgery is primarily performed for palliative purposes—to alleviate symptoms and improve quality of life rather than to cure the disease.
Surgical decisions in the treatment of melanoma are influenced by many factors, including the stage of the disease, the location of the tumor, patient health status, and the potential impact on function and cosmetic outcomes.
The treatment of melanoma, particularly in advanced stages, primarily includes chemotherapy, especially for targeting cancer that has metastasized beyond the primary site. In cases where melanoma is confined to the limbs or there are local and regional skin metastases, regional chemotherapy may be administered directly into the dermis. This method enhances drug delivery to the affected area, potentially improving treatment efficacy.
Radiotherapy is another treatment option for melanoma. This technique utilizes high-energy radiation to target and damage cancer cells, making the tumor more radiosensitive. By increasing the tumor's sensitivity to radiation, this treatment aims to effectively reduce tumor size and control the spread of the disease.