Metastatic melanoma frequently assumes the characteristic of satellitosis, i.e. metastases located in the vicinity of the primary tumor. In many cases distant metastases from the melanoma are found and appear as deep papules, plaques or nodes, devoid of pigment or sometimes brown, black or bluish in color. Lymph node involvement appears as a nodular swelling in lymph node areas. If the doctor suspects a metastasis, there are some tests that can confirm the suspicion such as lactic dehydrogenase (LDH) which increases in metastatic melanoma, even if it is sometimes negative even in the late stages and clinical tests such as CT, MRI, PET, l ultrasound, bone scan and chest X-ray, sentinel node study.
Therapy: chemotherapy (dacarbazine and temozolamide are in the first line even if we try to treat patients with combined chemotherapy which allows better results with fewer side effects), immunotherapy, radiotherapy (also topical imiquimod), topical diphencyprone (from 0.0001 to 10 %), palliative care to reduce pain. New drugs such as ipilimumab and vemurafenib have proven to be quite effective in extending the survival of patients with metastatic melanoma. Another field of application of surgery in the treatment of melanoma metastases is in the case of the so-called “in transit” metastases of the limbs. These are particular recurrences located in the limbs, with no other sites of disease. In these cases, the treatment of choice is hyperthermic-antiblastic perfusion with association of radical lymphadenectomy. The treatment, available and feasible only in a few centers dedicated to advanced oncological surgery, consists in isolating the circulation of a limb and connecting it to a machine for extracorporeal circulation which is associated with a heat exchanger. In this isolated circuit, kept at a temperature of 42-42.5°C, a chemotherapy drug (usually L-PAM) is circulated in association or not with TNF alpha and Interferon gamma according to the various schemes. This treatment is able to obtain a high rate of complete responses at the level of the perfused district, with a consequent improvement in survival. The average survival of patients with metastatic melanoma is 6-9 months after diagnosis with 10% of patients reaching 5 years.
We distinguish:
- Local recurrences: recurrence of melanoma within 2 cm of the primary melanoma
- Metastasis in transit: deposits of melanoma cells in lymph vessels more than 2 cm from the primary melanoma
- Nodal metastases: metastases that first involve the lymph nodes draining the area of primary melanoma
- Hematogenous metastases: the dissemination reaches the various organs thanks to the entry of the melanoma cells into the bloodstream
Frequency of metastases in various organs:
| Site | Metastasis rate |
|---|---|
| Lymph nodes | 70%-75% |
| Skin, fat, muscles | 65%-70% |
| Lung and mediastinum | 70%-87% |
| Liver and gallbladder | 54%-77% |
| Brain | 36%-54% |
| Bones | 23%-49% |
| Gastrointestinal tract | 26%-58% |
| Heart | 40%-45% |
| Pancreas | 38%-53% |
| Adrenal glands | 36%-54% |
| Kidneys | 35%-48% |
| Spleen | 30% |
| Thyroid | 25%-39% |