Melanoma – In Transit Metastases (ITMs)

What are in transit metastases (ITMs)

Melanoma also has the ability to spread via drainage channels in the skin called lymphatic vessels. Spread in this way can lead to melanoma cells attaching on to the lymphatic vessels in the skin. These melanoma cells then grow and present as small bumps which progress in number and size. These are called in transit metastases or ITMs. Another name for these bumps is ‘Satellites’ or ‘ Satellite Lesions’. The appearance of ITMs means that the melanoma has progressed to Stage III on the classification system.

Approximately one in ten melanoma patients will develop ITMs. Untreated, ITMs will enlarge, often causing severe problems with bleeding, infection, pain and offensive smells. They occur between the original melanoma and the regional lymph nodes, so for example, if a patient has a melanoma on the lower leg, ITMs may occur anywhere between the melanoma and the lymph nodes in the groin. Below are some examples of this condition:

There are many treatments available to deal with ITMs including:

• Simple surgical removal
• Destruction of the lesions with a laser
• Destruction using electric current
• Diphencyprone cream
• Injection of the lesions with a tumour-killing virus (T-VEC treatment)
• Giving chemotherapy to the affected limb (called isolated limb infusion),
• Targeted drug therapy for BRAF mutation positive tumours
• Systemic immunotherapy

No single treatment has been proven to be the optimal one. There have been virtually no studies comparing one treatment to another.  The treatments that are offered to patients dependent on many factors. You will usually have more than one consultation before deciding on your treatment. Often it is a case trying one treatment and then moving on to another one if it isn’t successful. The treatment of in transit metastases is complicated, which is why it undertaken in a specialist cancer centre. 

In general, patients who are assessed by the specialist as having mild to moderate ITMs are offered simpler treatments such as surgery, laser therapy, diphencyprone or virus therapy because the side effects are less and the treatments are easier to perform. Other patients with more severe disease are offered isolated limb infusion or systemic drug treatments to prevent the problem affecting the patient’s quality of life. 

Advantages and Disadvantages of Treatment

Many people are frightened at the idea of having treatment for cancer, because of the side effects that can occur. Some people ask what would happen if they did not have any treatment. Treatment can be given for different reasons and the potential benefits will vary depending upon the individual situation.

You can talk about your treatment options with your medical team and think about what feels right for you. It can be helpful to make a list of any questions you’d like to ask at your appointments. A friend or relative could also come with you for support.

If you have concerns about your treatment plan, you could get a second medical opinion. Ask your GP or specialist about how to do this.