familial dermatographia
Familial dermographism is a condition also known as skin writing. When people who have dermatographia lightly scratch their skin, the scratches redden into a raised wheal similar to hives. Signs and symptoms of dermatographia include raised red lines, swelling, inflammation, hive-like welts and itching. Symptoms usually disappear within 30 minutes. The exact cause of this condition is unknown. Treatment may involve use of antihistamines if symptoms do not go away on their own.