Groton's sign is seen in
Another form the rash takes is called Gottron's sign which are red or violet, sometimes scaly, slightly raised papules that erupt on any of the finger joints (the metacarpophalangeal joints or the interphalangeal joints). The most common signs and symptoms of dermatomyositis include: Skin changes. A violet-colored or dusky red rash develops, most commonly on your face and eyelids and on knuckles, elbows, knees, chest and back. The rash, which can be itchy and painful, is often the first sign of dermatomyositis Ref Harrison20th edition pg 1232
Dermatomyositis
SLE
Scleroderma
MCTD
Autoimmune skin disorders