The Casal collarorCasal necklace is a medical sign in which there is a redness and darkening of the skin around the neck, seen in people with pellagra.[1] It becomes prominent following exposure to sun, and can be itchy with a burning feeling and pain.[2] It can blister and weep, and turn into thick dark skin, with a coppery hue.[2] If prolonged, the skin becomes thin, dry and smooth.[2]
It is caused by a lack of the vitamin niacin (vitamin B3).[2] Seborrheic dermatitis may appear similar.[2]
The sign is named after Gaspar Casal.[3]
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