What skin condition is known for causing patchy hair loss?

Alopecia areata is the skin condition recognized for causing patchy hair loss. This autoimmune disorder can result in sudden bald patches on the scalp or other areas of the body. The hair follicles are mistakenly attacked by the immune system, leading to this localized form of hair loss.

In contrast, dermatitis typically involves inflammation of the skin and does not primarily lead to hair loss, while psoriasis is characterized by scaly patches often associated with redness and can affect the scalp but does not specifically cause patchy hair loss like alopecia areata. Vitiligo is a condition marked by the loss of skin pigmentation, leading to lighter patches on the skin, but it does not directly cause hair loss. Thus, alopecia areata is specifically known for its association with patchy hair loss, making it the correct choice.