Acral lentiginous melanoma
Acral lentiginous melanoma is a rare subtype of melanoma that mainly develops on the palms, soles, and nails. This disease is most often diagnosed in people of Asian or African descent. Due to the long absence of symptoms, by the time of diagnosis, acral melanoma has already spread to other parts of the body and has an unfavorable prognosis.
Due to the complexity and functional importance of the area of development of this type of cancer (arms and legs), surgical treatment is difficult. Tissue reconstruction is required during or after surgery. New treatments for lentiginal melanoma, such as immunotherapy and targeted drugs, are being used in clinical trials and are being prescribed to patients with cancer at the metastatic stage.
Lentigo melanoma — what is it?
This type of melanoma is characterized by the prolonged development of malignant pigment cells (melanocytes) inside the skin and begins as an expanding spot. The spot may be amelotic (unpigmented, usually red in color). Like other flat forms of this skin cancer, acral lentiginous melanoma has a number of features:
- the asymmetrical shape;
- uneven borders;
- color change (most often a mixture of brown and blue-gray, black and red);
- large spot diameter (more than 6 mm);
- ulcers and bleeding;
- rapid growth.
The genetic mutations that lead to the development of acral melanoma occur for unknown reasons.
Diagnosis of acral lentiginal melanoma
The main diagnostic tests for suspected acral lentiginal melanoma are dermatoscopy and biopsy. With the help of a dermatoscope, the doctor examines the affected area in an enlarged form and, if there are characteristic signs, prescribes a biopsy.
Initial confirmation of the diagnosis can be done with a small wedge-shaped biopsy. Thin and deep wedge-shaped incisions heal very well on red skin. If cancer cells are present, a second, more complete biopsy is performed – the surgeon removes the entire neoplasm with a narrow edge of healthy skin (1 mm). Sometimes, after surgery, it requires the installation of a skin graft from another part of the patient's body. With stage 1 lentigo melanoma, the prognosis is optimistic - the disease is curable in 99% of cases.
Treatment of acral lentiginous melanoma
The initial treatment consists in the complete removal of lentigo melanoma with a 2-3 mm edge of normal tissue. Further therapy (radiation, chemotherapy) depends mainly on the thickness of the lesion.
If nearby lymph nodes are enlarged due to the spread of metastases, they must be completely removed. To reduce the volume of the operation, the "watchdog node" technology is used. The lymph node is removed, where cancer cells can enter in the first place. If the excised tissue turns out to be completely normal, the remaining lymph nodes are preserved.
If the melanoma has spread to other organs, immunotherapy using the drugs Ipilimumab, Pembrolizumab and Nivolumab and BRAF inhibitors such as Vemurafenib and Dabrafenib is prescribed.
