Skin manifestations of amyloidosis can be apart of systemic amyloidosis or it can be a localized cutaneous amyloidosis. This is differentiated by the presence of systemic symptoms in the former variant such as numbness, tingling, fatigue, breathlessness, weight loss etc. Since you have itchy lesions in the arms, it could be the localized variant. However, presence of tingling does raise the suspicion of a systemic component. Localized amyloidosis of skin can be lichen type (most common), nodular, macular etc and the differentiation is based on their looks and histology. Please discuss this in detail with a skin specialist.
I have AL Amyloidosis, diagnosed last Dec. and currently asymptomatic with no treatment at this time.
I URGE you to go to amyloidosis.org and also become a member of the best support groups you can imagine at www.amyloidosissupport.com
Be VERY careful what you read on the internet! These two sites are state of the art, up to date and incredibly valuable.
All my best to you.