What is the skin condition called that causes U-shaped redness in the neck?

The skin condition referred to that causes a U-shaped redness in the neck is known as Poikiloderma of Civatte. This condition is characterized by a combination of redness (erythema), pigmentation changes, and atrophy of the skin. The typical presentation is a U-shaped band of discoloration on the neck, often resulting from sun exposure over time, leading to damage in the affected areas.

In the context of skin conditions, Poikiloderma of Civatte is significant because it highlights how environmental factors like UV exposure can affect skin health, leading to specific patterns of discoloration. This understanding is essential for identifying the condition and for guiding appropriate treatment or preventive measures, such as the use of sunscreen or protective clothing.

Other conditions mentioned do not specifically align with the U-shaped redness pattern in the neck, demonstrating that Poikiloderma of Civatte is the most accurate descriptor for this particular presentation.