After doing a quick internet search, if the diagnosis is correct, it is likely that a cure, from the standard medical approach, has yet to be found. However there are some suggestions on this site your client may wish to read about:
http://www.healthandage.com/html/res/com/ConsConditions/Amyloidosiscc.html#Treatment
There is always hope, and many people who have been
diagnoised with incurable diseases, seem to live years beyond what doctors expect. It seems that a large part of dealing with this condition, is keeping down inflammation, and changing the diet, lifestyle, etc.
Perhaps other than seeing his current doctor your client would consider working with a good acupuncturist or a Chinese Medical doctor, as they have an entirely different approach to health, working to support the body, & correcting the imbalances.
In the meantime, at least you are there, & doing what you can to help. That type of support is wonderful for reducing stress & simply nurturing the individuals you work with. While you obviously care, keep in mind that the journey here, is your client's journey and that your role is to be one of the guides who is there to light the path for him now. Be fully present, & hold the space for him to release his fears, & his sorrows as well as aiding him according to your level of expertise. Your role must also include being certain that his medical condition is not contraindicated for massage.
If it is cleared with the doctor, & you have the training, then Lymphatic Massage techniques may be helpful for any swelling. The itching may be occuring due to the swelling itself, though at the very least there are a number of over the counter anti-itch products on the market ( I would think however, that he should avoid any of those which are steriod based).
Best wishes for you & your client.