brimstone - an old name for sulfur. native sulfur, native sulphur. atomic number 16, sulfur, sulphur, S - an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions)
These patches of red, and sometimes irritated or itchy, skin can appear anywhere on the body, but they are most commonly found on the arms, neck, and face. These blotchy patches can be caused by a variety of factors, such as weather, genetics, allergies, or environmental conditions.
A blotchy rash on the elbows and knees is a common symptom of plaque psoriasis, a skin condition that causes skin cells to multiply up to 10 times faster than normal, according to WebMD. WebMD explains that plaque psoriasis causes red plaques on the skin that are often covered with loose scales.