I have only just come across this site. I was reading an old post about lipomas and hives that was archived on the site.
Can I just say that if you have chronic itching and any lumps – even really ones which are deep in muscles or fat, you should look into the disease called Dercum’s Disease, which is a very rare (but especially under-diagnosed) disease where you can have lipomas and angiolipomas everywhere.
These can itch very badly. There is also a disease called Mast Cell Activation Disorder which causes excess activation and excretion of histamines, therefore causing itching and this can be the cause of Mastocytosis.