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Welcome to healthcare magic

There is a condition called gottron's sign which is seen in dermatomyositis where you can see violaceous redness over knuckles which can extent to fingers and even upto elbow. Is your rash itchy? Gottron's sign won't have itching. A photo of the patch will help to diagnose. You can send it to johnyc305@gmail.com. Dermatomyositis usually will have associated weakness of muscles as well.

Skin biopsy findings will also help me to arrive at diagnosis.
There is another condition called Raynaud's phenomenon where hands and fingers can turn blue usually when hands come in contact with cold water.

Hope this helped.

Keep me posted

Take care

Dear Terry and Chris,
Welcome to Healthcare Magic.
So Nice to hear from the so caring spouse.
From the history it seems to be Purpura. This is a bleeding disorder in the skin where blood from the small vessels of skin gets accumulated under the surface of the skin. This can occur due to trauma may be strong enough to cause rupture of vessels in normal person or this can occur by trivial or minor trauma to the skin in persons having abnormality in the clotting factors of the skin. This is manifested as reddish patches to begin with and then turns to blue, black and brown color in next few days. This can occur on any site of body but the bony prominences are more commonly affected.
Now from your history it seems due to the first reason as your husband must be working where trauma may be factor in causing them. So you should not be worried so much. But even then we advice that your husband should undergo three simple blood tests- Bleeding time (BT), Clotting time (CT) and platelet counts. these are very cheap and easy tests and can relieve your tension. Other wise also gie your husband a lot of citrus (Vitamin C ) containing fruits.
With best wishes for both of your health,
Dr Sanjay K KNAodia